dude...if Final Fantasy XIII is your first, you're in for a shock, since the other games are nothing like it (most notably, they have much better characters, a lot of sidequests, and an actual GOOD story that makes sense from the beginning.)
You'd do well to play ANY final fantasy other than XIII, but you need to know that the battle systems in the other games are much slower, but you actually control them, so it's more tactical rather than basic.
VI is my favorite, but IV, VII, VIII, IX, X, and XII are all phenomenal. you seriously can't go wrong with any of them. IV is on PSP, VI is on GBA, VII-IX are on PSN store, and X is coming to Vita. XII is the only one that you have to get on PS2.
My Console Library:
PS5, Switch, XSX
PS4, PS3, PS2, PS1, WiiU, Wii, GCN, N64 SNES, XBO, 360
3DS, DS, GBA, Vita, PSP, Android
