Wait, why can't we pick FFXIV as our favorite?xD
At first I thought you wanted to keep the online titles out of it, but XI was there, so...why?

I was torn between FFII, FFVII, FFX and FFXII.
FFII was just awesome, mean and hard in many ways, and with a story I came to love so so much. But it was also easily exploitable and basically the story can't really hold up against the complexity of the newer ones.
FFVII was great in many, many ways and Crisis Core was - to me - the best game ever made, but since it's just a spin-off and the original FFVII didn't quite touch me like others did..hm.
FFX is easily winning in the characters/music/graphics departement which were all very likeable and nice, but not so much in other areas.
FFXII had a great story and I still can't say if I love Balthier more or the Gambit System, buuut..it was really hard to decide on a favorite xD
In the end I went with FFII because the overall experience was the best
But I bet I probably will be the only one who voted like that xD

I'm probably also the only one who absolutely HATED FFVIII and FFXI.