This Final Fantasy is easily one of my top five (along with 6, 7, 9, and 12).  The main thing I've always been fond of is the story.  It's a love story, through and through, and a powerful one at that.  The protagonist is unlike most, in that he's rather unhappy and antisocial in the beginning.  Over time, his character develops but it's a long hard road for him.  I won't spoil anything by talking about specifics, but this is very much a tale about people overcoming their personal demons in general.  This game also has a lot of replay value, as the story gets very deep and you'll always be noticing something new about the setting, characters, etc. on subsequent playthroughs.  FF8 does not spell things out for you!  Know that going in.