Too many to actually count, especially if I'd include all the crappy korean grindfests I spent way too much time playing. But of the ones I actually put some time into (in no particular order):
Guild Wars - Still easily the best MMO I've played, and nothing has come close to its great PVP and skill system
Vindictus - Out of all the instanced action RPGs I've played, this one was easily the best, and that's probably one of the reasons it's somehow still around despite being super dead playerbase wise.
Guild Wars 2 - A massive letdown compared to the original, but still a decent game I guess. Stopped after Path of Fire kind of sucked and because gearing for endgame was an unbelievably boring grind.
Dungeons & Dragons Online - I really liked how this was setup as a bunch of instances with some having actual puzzles and stuff, but it's a bit too dated to go back too.
Dungeon Fighter Online - Pretty fun, but also way too much grind.
Star Trek Online - The ship parts were pretty cool, but all of the story stuff seemed designed elusively for die-hard fans of the franchise, which I'm not.
Elder Scrolls Online - I bought this on sale and barely played it. I'll probably go back to it at some point, but between needing a sub to get the most out of it, the ugly visuals and the crappy performance, it's not really something I'm in a rush to get to.
Blade & Soul - I actually kind of liked this, although I can't even remember why because none of it was really all that great.
Runescape - Is there anyone who actually hasn't played it?
Destiny 2 - Left after Shadowkeep was a huge disappointment and it became clear that I'm 100% not the target audience of this game.
FFXIV - What I'm playing right now, and kind of the closest thing to Guild Wars in terms of being friendly to casual players and not demanding thousands of hours of grinding from its playerbase.
en.wikipedia.org
