I want to start a new free to play game in December. (I've done LOTRO and been pretty good at it, paid about 30 dollars in a year and a half and had enough TP to get Isengard).A rundown of all the F2P titles I play, even excluding LOTRO, is a bit long for the comments field, so my answer is posted below.
Which would you recommend for this? It seems like you've spent alot of time in EQ2, but I worry about the stability of that game (do alot of people really still play it)?
EQ2X
Update, December 11th, 2011: EQ2X has now been merged with EQ2 Live. I have posted an updated rundown of EQ2's new model, which is similar to what EQ2X but with some changes.
The EQ2X server is the game's most popular, so I doubt it's going anywhere. If you can tolerate limited bagspace, you can play completely free until level 80 (or pay the one-time $10 fee for silver status), which is a decent chunk of content, probably on par with what you got out of LOTRO.
One somewhat significant catch is that 2/3 of the game's classses and a similar portion of its races are premium unlocks for something like $7.50 (for one class or bundles of three races). I don't consider that completely prohibitive if you correctly identify what you want to play the first time (or if you're willing to tolerate a free race/class combo, such as my Half-Elf Inquisitor), but this is not necessarily easy if you've never played the game before. My advice would be to look into whether the new free trial program for the EQ2 Live game has started, so you can go in there to audition classes before committing to unlock one.
Unfortunately, your costs are going to go up sharply if you want to advance beyond 80.
SOE has yet to announce pricing for the new expansion, so I'm speculating that it will be $40 for an all-in-one box that also contains all previous expansions, which has been the model to date. If this is the case - look for news on this front over the next month - the all-in-one for Age of Destiny will be your best bet, as it would include Sentinel's Fate (2010's expansion, raised the cap), Destiny of Velious (Feb 2011's expansion, more AA's and all of the new content including the next year), and Age of Destiny (presumptive release in the next month or three, another AA cap increase, will also contain the Beastlord class if you're so inclined). Whenever AOD launches, it's probably safe to bet that SOE will hit you up for another $40 within a year.
In addition to expansion boxes and character build options, non-subscribing EQ2X must pay per item posted to the broker (last I checked, this was something like 10-20 cents per stack), along with 50 cents per spell upgraded to the Master level and 50 cents per piece of legendary/fabled/mythical gear unlocked for use on the non-subscription tier. Starting in DOV, the first expansion launched after EQ2X, there is no more gear of lower than legendary status, even from solo quest rewards, so you will be hit for that fee early and often. The good news is that this will still work out to under $15/month if you're running dungeons - how often do you get 30 loot upgrades in a month? - but the bad news is that it is going to be a recurring cost in a way that LOTRO's content unlocks aren't.
Finally, if you care about endgame group content, you might want to investigate what the demographics look like. The low levels are definitely dominated by free classes, but there are definitely more players in these level ranges than you'll find on the live servers, but there are by definition no complete freeloaders at the level cap, and many are transferred characters from the live service. (Note that this is a one-way transfer.) I haven't put in the time to determine whether the upper levels have a skewed population, how the grouping scene is, etc.
(Full disclosure: I have not copied my character over to the F2P server, even though I would probably pay less under that business model than I do for my occasional one-month visits to the live game.)
Runes of Magic
Again, the good news is a low barrier to entry - I would recommend purchasing a permanent mount (under $10 even at the bad exchange rate with no sales), and this is the only thing you need between level 1 and 55. Depending on how much you enjoy experimenting with class combinations, this could last you a while.
The bad news with ROM is the major investment - you have a bit of choice of investing time versus cash - that it takes to enhance your gear as you get to higher levels. Some people have gotten to the highest tier of content without paying a dime, but they may or may not value their time less than you do. There are shortcuts - it is possible to unbind your old, fully enhanced gear and sell it for gold, which you then use to either buy someone else's old gear or to pay someone else to buy you cash shop items to enhance your new stuff. Again, though, you're looking at a recurring cost. Because this cost is per gearset, it also means strong pressure not to continue to use more than one of your six possible class pairings.
DCUO
Good news here is that, as I posted this weekend, non-raiders can get a free ride for the entire launch game, and I doubt they'll be able to produce DLC often enough to be prohibitive on your pocketbook. Bad news is, I don't see how this model gets them more revenue, because 1000% more players who pay $5 once is not a lot compared to what they were expecting with a $60 box price and a $15 monthly fee.
Games based on licensed IP's are the only games that SOE has ever cancelled, and I do not have much confidence that this one will avoid that fate unless I'm deeply mistaken on the longterm revenue potential of this model . That said, it's a pretty darned good ride to get for mostly free, catch it while you can if you're so inclined.
DDO
This one is last on my list because I figure that you probably already considered and rejected it if you're already playing LOTRO and looking elsewhere. If you're not in the mood for the game's action combat, there's no real helping that.
The good news is that, like LOTRO, you're looking at a model where you only pay when you want more content, and you get to keep everything you unlock indefinitely. It's also completely "stable" to the extent that it's been on the F2P model for the longest and shows no particular signs of giving up ground.
Summing Up
I may or may not have fully answered the question, in part because I'm not certain exactly what you're looking for. Maximum reasonably fun solo questing time for the money? Access to endgame content with no recurring real money fees?
My best advice is to try a bunch - these and others that I haven't gotten to yet (e.g. the Cryptic games, Age of Conan, Fallen Earth, Allods, Pirates of the Burning Sea, Wizard 101, probably many others). The biggest advantage we the consumer have in the F2P marketplace is that we can try more than one of these before we make some big commitment in time and money.
That said, my paradoxical conclusion is that the most gamer-friendly "free to play" models are the ones that are in the business of charging for content, as LOTRO/DDO do. Under this model, the developer is forced to keep the game fun and deliver content often, or not get paid. Models that are designed to have recurring payments may or may not be an improvement over $15/month - for EQ2X I'd say that answer is yes and for ROM I'd say probably not - but my experience has been that this encourages the developer to make the game require more of whatever it is that you're paying them for.
Edit: LOTRO
Joe in the comments here asked for the LOTRO summary.
The game mechanics of LOTRO are going to be much more familiar to WoW players than something exotic with click-to-swing combat like DDO or DCUO.
You're looking at a more standard MMO hotbar setup with autoattacks, global cooldowns, etc. DDO is more of a lobby-based world with all the action happening in group-sized instances (up to raid size), while LOTRO's standard MMO quests happen in non-instanced open world zones. Note that combat is definitely at a slower pace than you find in WoW, which may leave you feeling like kill ten rats quests are tedious because they're taking way longer than you're used to.
Unlike DDO and EQ2X, all of the races and all but two of the classes are available for free players. With DDO, you might start a character that you have to re-roll once you've decided to pay, and that will not happen with LOTRO unless you have your heart set on a Warden or Runekeeper. You can advance into the late 20's without paying a dime, and what you see is basically what you're going to get going forward.
One weird quirk to LOTRO's model is that there are a number of things that are permanently unlocked on a per-character basis for any character that you sign onto while you have a valid subscription. Bags, currency cap, trait caps, riding skill requirements (provided you'd rather do a tedious questline than pay 50 cents), all go away with a single month's subscription, which also includes rental access to all of the level 1-50 content and 500 Turbine Points for future use. The best value for your money is to level until the end of the free content, then pay for a single month of subscription (so that you're ready to use the content you are only renting) and see where you stand at the end of that month level-wise before you decide what else to purchase.
In LOTRO, you are never obligated to pay for level cap increases - if you are prepared to grind away at mobs and repeatable level-scaling content (e.g. skirmishes), you can in principle reach the cap eventually. You will also have free access to the game's epic story quests (generally the best content, worth doing even if you don't need the exp), whether or not you pay for the associated zones. If you do think that you will pay for the current expansion, which costs $30, spending an extra $20 (for a total of $50) for the "legendary edition" will get you enough content to get from level one to the cap, all of the new endgame content, and 1000 TP (plus what you earn while questing).
One downside - in my personal opinion, which others may disagree with, is that endgame group content is not Turbine's biggest priority. There is a single new raid in the expansion (a single encounter, not a full dungeon), and three group (6-player) instances that will in principle be implemented in the patch three months after the expansion launched. The previous expansion launched with a single raid, a single group zone, and three three-man zones, and added a couple in a patch a bit over a year later. Turbine has tried to make due with less, focusing on revamping old instances to scale with player level, but the bottom line is that LOTRO gets new dungeon content at a slower rate than any of the above games.
That all said, LOTRO may be the best choice out there if you want a traditional fantasy MMO. The game stays true to the lore, which means just the four Tolkien playable races, no flying mounts, and the occasional klunky work-around for minor details like death and fast travel. It's clear that they spend serious time making Middle Earth work as well as it can within the MMO genre, and that is a good thing if you like Middle Earth.