LogFAQs > #896191673

I've played them all.

Overall, Tactics is #1, no contest. Game's pretty much flawless in both gameplay and story.

Now, main series it would probably be:

VIII (First FF I finished, only bad thing is the draw system, but card/item modding solves that)
X (Beautiful game, way too easy though)
VI (Best story overall IMO)
VII (Golden era of JRPGs on PSX, a true gem)
XIII (Really fun combat, I don't mind the linearity)
IX (Great nod to older 2D FFs, but I agree that it's overrated by nostalgia freaks)
XII (Amazing combat, gambits were very well implemented so the semi-afk grinding was cool IMO)
LR (Really fun combat)
XIII-2 (Closest thing to a Pokemon/FF hybrid. Time travel was done well too)
X-2 (Lots of content on this one. Didn't like being unable to skip cutscenes without compromising completion %. Turned replayability into an issue)

Then everything else for different reasons.

Special mentions to Crisis Core and Type-0, both very good portable JRPGs with lots of hours to enjoy.
---

The side of the fence that we climb determines who's afraid