Three is best on DS. There is no PSP for it, sadly. The PSP makes 1, 2, and 4+ outstanding to play! 3 is still mediocre, but not unbearable. The grind is real.
The originals of the 2D FFs do not age well. Each of them have some pretty disappointing flaws that remakes fix.
Nearly half of the magics in 1 don't work right.
Encounter rate of 2 is way too high.
3 isn't balanced well at all with difficulty spikes galore. (retargeting still doesn't exist in the remake and there are still some sharp difficulty spikes, though fewer of them.)
4 has a disappointingly small inventory system and never gives you a choice of party members.
5 and 6 have a PSX port that don't differ enough from the source to make them worth playing. They're basically the SNES versions with longer loading times and some translation fixes. The GBAs and on use a better script and have additional content. The mobile versions at least have a decent viewing aspect, but the Steam ports look ugly as sin with background tiles that don't match up and sprites that don't look like they were designed at the same time.
FF7, off course, has not officially been remade or updated at all. Any release after 1998 is just fine, but the music and FMVs suck on PC without mods.
FF8 should be on steam. No mods needed, but there are some that make it look "better".
If you can get your hands on 12 Zodiac Age you might find it fun.
