Part VIII is when the series really starts to take a nosedive.
I agree that FFVIII was a complete nosedive - that game is horrible. I've tried to play like 3 or 4 times, twice getting close to the end (last disc) but that game is just too tedious. Characters are dull, locations are uninspired, the whole story is just lame and the battle system was bad.
BUT... FFIX is a completely different story.
I played FFIX when it came out and I remember it being so full of charm and character. It was the only 3D FF game that felt like the classic 2D ones.
And it's not just about the return to the "Crystals" theme or the classes included. The game just flowed, it actually felt FUN again. While serious at times, it was also lighthearted and had such a loveable cast. The gameplay also felt brisk, moving at a perfect pace. And the graphics were also amazing at the time, and they still hold up well today.
I would have to replay it again today to see if it is my favorite, not sure (FFIV and FF VI are tied currently). My PS broke down ages ago and I was a Gamecube guy last gen, hehe - so as soon as I get a PS2 (getting it just to replay FFIX, FF Tactics and Brigandine!) I will find out.
But definitely give FFIX a chance, especially if you liked the earlier games in the series.