Draw system + Junction system.How could you possible like 8 more than 7 or 9?
*Just trying to get you to rant and rave about it*
Analog controls without chibi-ish characters (the characters in FF9 were bloody annoying). Last time I tried to revisit FF7, I couldn't get past the lack of analog support. The whole Shakespeare backdrop of FF9 was cool, but the characters severely limited its effectiveness for me.
The summons / GFs felt like they actually belonged instead of being something you could totally ignore. In FF7 and FF9, you could mostly ignore the summons. I mean, seriously - how many times did you summon Knights of the Round and sigh out loud? It was everytime except for the first for me.
Triple Triad.
Also - Ragnarok. There isn't a better airship then Ragnarok. Period. The ship looks cool, and it's a space ship being used as an airplane. Oh, and it's name is cool.
The protagonist characters in FF8 were best to me, too. Being a kind of antisocial teen with only a handful of friends, Squall was relatable. Zell was like that annoying guy I went to school with. Rinoa was that dicktease ex-girlfriend I had. Irvine was my best friend's alter-ego. Selphie and Quistis were throwaway characters for me, but there are people like that in my life as well. I'll admit that there weren't any iconic villains in FF8, but I was okay with the enemy being a collective of Sorceresses. That stopped the villainy from being characterized by a single set of manners in one character, much unlike FF7 with Sephiroth and FF9 with Kuja. Also, it was good to not have any overpowered optional characters like Beatrix, although she was my favorite character in FF9.
If you need more, please say so. :-D