Late PS1, Early PS2
The reason being Final Fantasy IX and X are my two favourite Final Fantasy games EVER.
People say VII and VIII were amazing, while IX was terrible, sure, I can live with that, although they never give a proper reason, but what feels more of a "final fantasy", a sci fi environment, a game that revolves around a school, or one that varies so much in style with the characters and environment, which also, in my opinion, has the better music too.
I just feel that IX was so different to what we'd seen in VII and VIII that it was great, it felt like one of the earlier games in terms of weapons/environments, but was so different too, I just loved playing through every bit of it.
And X, well, that's just a no brainer, it was amazing back then, and it's amazing now, I'll never dislike it... ever. I think X-2 was just embarrasing for the game, it didn't need a sequel, the ending was perfect!