The Final Fantasy series has a long history of good games, although there’s some definite staleness in the later releases. FFX was a step in the right direction, but I’m waiting to see what they do next before I pass judgement on the future of the series.
Personally, I’m not a big fan of the PS1 games (7-9). IMO, the peak of the series (so far) was 3-6. 1 and 2 originated a lot of what you take for granted in console RPGs these days, but they probably won’t capture your interest to any great degree.