I'm having fun with City of Heroes. It's a bit old now, but it still gets plenty of support from the developers, there's even an expansion named Going Rogue (not to be confused with the book by Sarah Palin) coming soon.
CoH is kind of a shallow game, though. Don't think of it as a stats/gear based RPG, think of it more as an MMO Beat 'em up with RPG elements. You usually fight groups of weaker enemies, from 3 to 20 on one, depending on how powerful your character is. This, by the way, gets a lot of CoH players killed when they try other MMOs. Three orange conning minions are fodder at mid-high level in CoH, in other games, it's usually certain death. Also, nothing decays in the game if you decide to not play for a week. It's actually impossible to lose progress, short of a server rollback, of course.
The community is surprisingly good. When new players ask for help, they usually get it, often with some kind of gift thrown in for being new to the game, usually enough "Influence" (money) to outfit your character well into the 20s, more if you have a great looking costume. I've seen people get millions of influence just for that. It's one of the nicest game communities I've seen.
One factor in why the community is great could be how loose the teaming structure is. The holy trinity of Tank/Healer/Nuker? Eh, leave that at the door. In fact, don't say the word "Healer" out loud, it's a sore spot for some of the Defender class players. Teams in CoH are more rag-tag. Some powersets are usually more than welcome, like the offense boosting "Kinetics" powersets, but everone is useful. Special note goes to the absurd power of Buffs and Debuffs in CoH. It's not unheard of for a single character to increase the defenses of a character tenfold, boosting damage to the class' cap, or completely locking down and severely debuffing 16 enemies at the same time.
Should probably also mention the Sidekicking. Got a pal who is 15 levels higher than you? Join his team and you're now his level-1. Want to play your missions? Have him join your team and he'll scale down to your level. He'll still get xp, of course.
The reason CoH gets away with this is that it's kind of easy. Sure, jump a Giant Monster with a Blaster (the glass-cannon class) and you'll soon meet the floor, but the hardest raids in the game are usually done in pick-up groups, with a wide variety of powers. Speaking of Raids, there about 6 high level "Trials" and "Task/Strike Forces" in the game. It's not really a focus of the game. You're just as likely to get the game's version of uber-loot off a street thug as you are facing down the entire Freedom Phalanx at the same time. Good luck with that one, by the way. CoH is one of those games where it really is about the journey, not the destination. CoH starts at level 1, not 50. It kind of ends at 50, really. Which is why you get 12 character slots per server.
Finally, there's the costume creator. Because where there's superheroes, there has to be spandex. Power armor. And business suits. And sailor suits. And plant and rock parts. And wolf and dragon heads. And fantasy armor. Capes unlock at level 20, though. And you can mix and match, plus add patters to most of the things. Although, the costume creator is hard to explain, and has been topped mostly by Champions, it's still my favorite part of the game. If you can imagine the superhero, you can likely make it. Just, make your own. The GMs disapprove of trademarked ones.
I think that's about all. That got a little longer than I thought it would. The short version is that CoH is a nice casual MMO. You log in, do a mission or two, solo or teamed, and you've made decent progress for the day while playing a hero of your own design. Also, CoH just got superheroic flight right. Really, the first character anyone makes should be able to fly. It's kind of a rule.
