I can't really comment on WoW, so I'll give my pros/cons of FFXI.

I quit around the end of December, so maybe things have improved, maybe not. Around the time of quitting I was trying to level some lower jobs of mine (Lv30-40) jobs and had a hell of a time finding a group. Earlier posters are right, unless you have/or make a nice group of friends it's going to be very time consuming to get a group together and actually level up, since most people are spending their time meriting their Lv75 jobs now.

I loved sticking with FFXI though because many of the story archs were fantastic. I still feel like the Chains of Promathia story line was probably one of the best games I've played, crappy dungeons and being level capped sucked, but the boss fights and cut scenes were worth it.

I guess what i'm saying is this, if you can put in the large amount of time to make a solid group of friends (probably in your same experience range, or not) you'll have a much easier and more enjoyable time in the world.

The game is exactly the same on PC, 360, and PS2.  The only difference is that the 360 has better graphics (as stated above), a larger draw distance (though it has no effect on the appearance of the monsters, those are the same), and achievements.

 So get it for whatever machine you'd like to be hooked up to for hours at a time.

Pokemon Pearl:
Trainer Name - Emiger
Code - 3866 4499 6428

Please, just PM me with your code if you add me.  Hope to see some of you in game! :D