I've never played FFXI. A friend of mine had a lot of fun with it, but finally went cold turkey and deleted his account.
Myself, I play WoW, and have for about two years. Started up on Spirestone as Horde (which is, my heart, my true alliance) but quit due to it taking up too much time. Then went to Kael'thas where I play as Alliance.
I used to play both. WoW got boring after the first month of playing. After soloing myself to 25 I got bored because no one really wanted to group up unless you were in a guild. And from what I've seen the guilds are pretty much run by 15 year olds or 30 year old cat-piss-men who live in their parents' basement with no life who sleep like one day a week (usually when the servers are down for updates). FFXI was fun, I'd still be playing it if my group didn't split up for college and got busy after that with work. Right now FFXI from what I hear has gone the way of EQ, all pros no noobs so everyone is high level with no interest in grouping with noobs for low level runs.
I only got a chance to play FFXI (PS2) but thanks to they narrow payment methods I stopped playing it about *counts* almost a year now, since I get no sort of e-mail about events from the game, and the fact I'm left in the dark in keeping contact with my linkshell. I never found a reason to go back other than finish leveling Dragoon, even after when I just got the newer extension at the time. Leiona, Seraph Server.
I used to play wow, Dragonmaw.. 63 Holy spec pally and on the side a 60 rogue.. pve specced I think. I had a bunch of the other classes, but money and my grades started to plunge so I stopped. I want to go back though!
I never tried FFXI since my boyfriend did and said he spent the first 5 minutes with his character slept.. or something like that so he instantly quit. We both got WoW and have been playing it since release. Horde also, I have 3 70 druids and a 70 mage on Cho'gall.... I play too much probably D: