I'd go GW2... Final fantasy MMORPG's just have never been that excelent (graphically tho... I'd argue otherwise, but not always about the graphics, look at WoW).
I bought the PS3 for FF13, bought the PSP for crysis core (ff7 prequel), but, totally skipping the MMORPG releases for the FF series.
Square enix makes great games for single player... but the games for multiplayer, just isnt well made in terms of gameplay/balance/sociability, which really, is what WoW has.... however the graphics turn many people away.
I'd say, GW2 will be more or less like wow, with better graphics and less game play features (judging by previous experience)
go both, FFXIV is out now and you get a 30 day free trial, last time I checked GW2 was free you'll lose £20-30 pounds somewhere but hey there both different games I'm expecting more from SE FFXI - was flawless