Absolute favorite? That's tough. I'd have to go with my first, which was EverQuest, although there are things about other games that I think are better.
Best Character Creation - City of Villains. Probably City of Heroes, too, but I never tried it. Screw being the good guy... I like being BAD.
I could spend hours just making one character. It's like a mini-game in itself.
Best Skill/Character Development - EverQuest and its AA (Alternate Advancement) system. Being able to enhance my characters through other means besides levels and equipment is nice. From little things like faster innate run speed to dramatically increased damage, I can make my character amazingly powerful. And there is almost no limit in the number of enhancements you can do.
Most Satisfying - Final Fantasy XI. That game is so freaking ass hard that when you actually accomplish something, you feel like cheering, dancing, and having a celebratory glass of champagne.
Casual Fun - Probably World of Warcraft. It's easy to pick up and put down. WoW is my family time, too, so that might be why I like it so much.
Current Fling - Pirates of the Burning Sea. I'm enjoying this so far, but I'm feeling a bit apprehensive about the depth of character development. I'm hoping that the fighting styles branch out more or something, but I'm guessing that what the game lacks in on-land gameplay depth, it makes up in ship to ship open sea battles.
Most Anticipated - Star Trek Online. If it ever comes out. That game has hit more snags that I want to think about. I'm such a massive trekkie, though. I will play it no matter what.
And in case you're thinking that I put everything I've played on my list, the following games were ones that I've played and didn't make the list:
Sword of the New World
EverQuest II
Vanguard
Guild Wars
Star Wars Galaxies
Lord of the Rings Online