re: FF VII, VIII, or IX ?

Since you're enjoying VI right now, I'd go with IX. I wasn't a big fan of IX when I played it when it was released, but I played it again relatively recently and really really enjoyed it. It really is a well done throw back styled game, from the leveling up specific abilities to the character customization that doesn't necessarily allow for every character to become an ability carbon copy of each other.

VIII, to me, is the game of the three that has not aged well. While VII is no longer graphically impressive, it is easier to overlook the polygons then just the straight up poor resolution of VIII on modern TVs. But note that this might only be a problem if you're playing the old PS discs. I haven't downloaded them and played them since I still own the originals.

VII is quite the RPG accomplishment. And normally I'd say to go with VII first (for the same reasons already enumerated in this thread). But I also like VI more than VII (and I grew up idolizing II/IV so the Ye Olde Fantasy type really gives me a nostalgia rush) so I think IX will suit you better. Plus, IX has a killer soundtrack. Simply one of the best scored FF games in the series - which, I believe, is really saying something.

For the record, I'd say Earthbound is my favorite RPG, and I would heartily recommend that you go and figure out how to leave Onett and get to Twoson. The game is tremendous and you're missing out on a lot.

And if you're looking for something more new school that plays like polished old school, I'd recommend giving Dragon Quest IX on the DS a whirl.

Happy gaming. You've got some good choices there so as long as you eventually cover them all you'll be okay.