The most recent game I've got into is Guild Wars 2.
I'm not normally a fan of MMOs, but Guild Wars 2 removes enough of the things I don't like for me to really enjoy it. There's no subscription fee, so I can still go off and play another game for a few weeks without feeling like I'm wasting money. Loot and resource nodes are player-specific, so there's no fighting over them. And everyone who contributes to a kill/event gets experience and/or credit for it, so there's no queueing up to fight the same boss and plenty of encouragement to help each other out. As a solo player, I can stumble across a load of other players hacking at a giant monster, and just wade in and try to help, even if both the players and monster are way higher level than me!
Oh, and you pick up quests by just wandering into the area they're happening in, which removes the need for NPCs with exclamation marks above their heads. This may seem like a small thing, but it means you can very easily end up just wandering around, exploring and running into quests until you realise it's past midnight and you've missed two meals.