City of Heroes/Villains is the only MMO I still play (aside from occasional bouts of free MMOs... But as someone said earlier, they're just big pointless grinds, so that never lasts)
Asheron's Call I also love (the original, not the worthless sequel) but don't play anymore. It was a fun game, with great dungeon design, constant updates and new content, and no 'instanced' dungeons, all static and well designed dungeons, generally with some reward at the bottom. It was, however, a massive grind-fest whenever you weren't questing, and quests got you nothing in the way of experience, so that got old after awhile.
CoH/V I love for the feel, mainly, and the pace of combat. Most games (lineage 2.. I'm looking at you) don't understand that combat needs a proper pace. Typically it should be fast, but not so fast as to be confusing. CoH nailed the pace perfectly for me; any type of combatant character will clobber the lower-ranking shmucks (as any kind of super SHOULD) and only get into long fights with rarer, tougher baddies that only appear as a mission-end or with large teams (and large teams waste them in seconds, as you should in a 8 vs 1 fight).
While I can't compare it to WoW as I've never played the bastard and never intend to, I'll just compare it to most other MMOs I have played: CoH is far more immersive, giving your character an identity other that dipshit #1427 with armor and weapon x and y, as well as assigning some level of story to every mission you did. The story lines are optional, of course, so grind-happy sods (i.e. most players, including me most of the damn time) can happily ignore whatever the NPCs are saying and go pummel a succession of enemies, most of which only have slight differences, while some require drastic changes in tactics to tackle, especially solo. However, the story that goes along with each mission does help pull me into the game and makes you feel more like a hero (or a villain... whatever) than you get from just running around beating people up in the name of xp and loot.
Speaking of loot... I personally love the loot system in CoH/V. Loot is distributed automatically, so there's no need to fondle some corpse (er, "unconscious guy" for Hero-side) looking for a few pieces of whatever currency and a rare item he inexplicably refused to use against you. Again, this is a part of the whole 'pace' issue; CoH/V doesn't feel the need to break up the action after every fight for looting, and this is a good thing since any fight with a large group involves huge numbers of enemies, meaning it would be a giant cluster-fuck if 8 players had to figure out what loot from each of 25 foes goes to which person; and that would be after each fight, which lasts from 10 seconds to 1 minute depending on damage output and overall competence of your crew.
I don't know that it has better graphics than WoW, but since I've heard WoW described as having a 'cartoony' look, I wouldn't be surprised. CoH/V goes with a 'comic book' look, both in the people and the world. This means it isn't exactly 'gritty' and 'realistic,' but it is stylish and pleasing to the eye, mostly.
While CoH/V naturally contains grinding, probably as much as any other MMO, it at least tries to break it up and make it seem more Heroic/Villainous than simply "go to location x and smack people around." I know not too many people share this opinion, but I love PvP in CoH. Team PvP requires a bit of thought and strategy. 1v1 PvP is a bit less sophisticated, mostly focusing on whatever you did to trick out your character, and often becomes a rock-paper-scissors thing whenever you are fighting a different archetype.
Crap I just realized how much I wrote here. I'll shut up now.