FF1 - Decent game and what started it all, GBA or PSP are the best versions.
FF2 - Bleh, the leveling system in this game blows and is easily exploitable. GBA or PSP.
FF3 - Never played it, but I assume DS version is the best.
FF4 - Considered one of the best versions. PSP probably is the best.
FF5 - Never played it, but GBA is probably the best version.
FF6 - My favorite of the series and considered one of the best RPGs of all time. GBA version.
FF7 - The game that started the RPG invasion in the west. Can get it on PSN, if you have a PS3 or PSP.
FF8 - Personally, I didn't like it, but many people do. Can get on PSN.
FF9 - Return to the old school style and one of my favorites. Can get on PSN.
FF10 - Great gameplay, didn't like the characters. I'd wait for the HD version.
FF12 - One of the highly debatable ones. I loved it. I'm sure this one will get a HD version, too, at some point.
FF13 - Great battle system, mediocre story/characters.
