Open world. XII introduced this both to FF and to me personally and nothing really felt as good as having incredible exploration on top of that unique FF flair. Still have a big soft spot for the traditional world map, though. The linear approach, not so much, since the games in the main series that follow that format are basically my bottom two FFs ever (not to mention some of my least favorite games in general). I mean, it can work, since I still liked Xenosaga, but FF just can't handle it well, at all.

(And before you stone me to death, keep in mind that this is just my opinion, you're entitled to your own and I won't judge you for it, and, most importantly, I love you)