I play VII mainly for nostalgia; IX holds my interest more. VIII is a guilty pleasure, given a few aspects of the game (Rinoa, primarily). FFXII had a great world, but the politics, the villain and the half the main cast almost spoiled it. I'd play VI again, but the caves.. I find it really tedious to navigate VI's dungeons. >(
There used to be FF GPSLs around, but I don't know what prompted people to stop advertising FF..