Haven't replayed XII for a long time, but i thought it was a new favourite when I first beat it over ten years ago. Replayed X recently and it's great though I wish there was more variety in enemies, the postgame was a little less arduous, the minugames didn't suck so bad, blitzball wasn't so shitty, and the sphere grid had some more qol features to not be such a chore. They had some damn obsession with stupid rng mechanics for these ps2 ff's, X had a lot of dumb shit, and XIIs postgame while very fun was annoying af with those random chests.
Plan to replay XII on pc where I assume I'll be able to fudge the stats and get better hit rates on those stupid chests. X is my favourite, XII is great but the main questline could've used more time in the oven and the rng chests really, really piss me off.
I'd vote X-2 also but not available so I threw a vote at XIII. XIV seems good, I got a char to lvl 60 a whole back and enjoyed my time with it well enough but I also just can't stay focused on mmo's.