My first MMO was Ragnarok Online, in that I installed it and the University network blocked me from logging in.
Then I tried ROSE Online, and played it for about... 3 days. It was okay.
Then I got into the beta of WoW and have played it pretty much ever since. I tried out most of the "WoW-killers" - Warhammer, Rift, SWTOR, TERA, Neverwinter, Guild Wars 2 - but rarely played any beyond the first month and in the case of TESO, not even past beta. Wildstar I'm still on the fence about too.
The only other ones I've played for any substantial period of time are: FFXIV: ARR, which is basically just a prettier, but slightly less polished FF version of WoW - even then, I think if it wasn't for the Fat Chocobos LS, I probably would've dropped XIV a long time ago.
The other one I still play is The Secret World - I bought a life time sub for that near launch, because despite all it's flaws (and there's a lot of them), the game has a really deep and interesting overarching mythos and storyline and it's great the way they extend this out of the game with things like ARGs etc.
Although I'm pretty bored of WoW these days too.