Everquest 2 mostly. Started that about 5 years ago. Would play for about 6-10 months and then stop for 4 or 5 and start again. I played Tanks when I could but usually ended up healing - my favourite class was the Dirge though, a dark troubador that could bolster his allies, debuff his foes and look good while doing it.

Took me several weeks, if not months, to become a "decent" players. The game is customizable, the crowd is mature (albeit elitist sometimes), the game has a lot of End Game content and a skilled player will make a big difference in a group. An issue is that if you have a full time job and don't play at least 4 nights a week for 3-4+ hours, it will be difficult to Raid in a serious Guild (and get the End Game gear). I remember that the most hardcore guild on my server would Raid 7 nights a week.

The crafting system is awesome. You can create armours, weapons, spells and make some decent money out of it. It does tend to make the Economy a bit more reliable on virtual currency than a game like WAR though. So you have more Gold Farmers (or Plat Farmers as we called them in EQ2). The player's house is a great addition and it's fun to decorate your place during an evening for some "lighter gaming".

I tried Vanguard when it came out but the Elfs were so friggin ugly, I couldn't stand looking at my toon while playing. Other issue was that of my 30 days sub that was included with the game, I couldn't play for 3 weeks because of bugs. I never bothered harassing SOE to get those 3 weeks back. Game seemed interesting though, lots of possibilities - build your boat, etc. And the universe seemed mature and realistic. Got the Collector for that game and it's sitting on a shelve, all pretty.

I did try Conan on release also but the game didn't feel finished at all. Mobs would respawn a mere second or two after you killed them, item icons were all the same, levels were too linear, Server pop was a nightmare and so on. Other annoyance was that the game promised 10 "buddy keys" when you bought a Collector Edition - and that's the reason why I bought it since I had a few friends that wanted to try it at the same time, start a Guild and so on... - but those keys were only made available several months after the release as I learned after purchasing the thing. Another factor, to get even more people to play, was that the game was supposed to come out for Xbox 360 and never did (Fun Com said that "...programming for the Xbox360 is a bigger challenge than we expected". The game looks good and they supposedly improved it a lot since launch but I doubt I'll go back. You only get a single chance to make a good first impression and Fun Com blew it.

WoW... only tried the trial two or three times. The gameplay is very simple, the game is well polished, there's a good atmosphere but I never liked the graphics or most of the community. And never could roll a toon that I felt like playing much. The Night Elf Hunter was prolly the character I preferred the most... but even then. And now, well, the Engine is outdated.

And some shallower experiences...

DAoC... played 30 minutes. Maybe an hour. Engine totally outdated and gameplay blows.

Star Wars... tried the trial for a few days. Is the game supposed to be fun at some point?

Probably tried a few more, but EQ2 and WAR are really the games I played and enjoyed the most.