My FF history is a bit all over the place, and thinking on it, I've never actually beaten a mainline game.
I will say people should totally give X-2 a chance for the gameplay. Super fun.
I ended up over my friend's house after school, and between him and his brother they had alot of square stuff, which was cool. I couldn't afford it all myself, so I at least got to see parts of 8, 10, X-2. Unfortunately, it wasn't my game so I would miss pretty big chunks of things as he actually played in his spare time himself - he would consult me for harder parts sometimes(which is strange, because at that point I mashed just as much as him in Guilty Gear, trust me!). Then there was the fact that when I played FF8 on his Mac, the save kept deleting(I guess, looking back, he was deleting it? or Macs suck? ) so I never made it far there. I've sort of detailed in how my TV time was limited on this forum before, but I only spent a short amount of the school day actually at home with access to a TV. Ultimately, I think that influenced my purchases, and the fact that I've only completed FF side games:
FFTactics, Tactics Advance, A2, X-2. I do have I think III on the DS, but it's a bit of a slog as much as I love job systems. Might be worth revisiting when I'm desperate for an exercise bike game or something.
Strangely enough, all of those involve a job system!
I did actually come pretty close to beating X and made some progress in XII, but my PS3 broke. Twice.
I was only really concerned with getting the perfect ending in X-2, so I used an exploit where if a character was holding an item that powered them up if they were low health(which you got fairly early in the game, and IIRC multiple of), each hit they did did 9999 damage. So pop it on a class skill like the (Gunslinger's?) Trigger Happy, where you do as many hits as fast as you can press a trigger button, and even the final boss can be beat fairly easily. This was fixed for international versions, and although I like having the easy mode, international version also had new classes which I was jealous of.
Wish C&R wasn't done with the series as it'd be cool to go back to some of these now that I am free from broken PS3s and remasters and remakes and rereleases are out there.