I think the most standout thing is that the tone isn't afraid to be goofy or serious or romantic when the time comes for it and it nails all three of them.
The same game that had the iconic Aerith's death scene or Barrett's flashback with Dyne also had cloud going into a homoerotic gym for a crossdressing quest and Tifa slapfighting Scarlet on top of a giant phallic cannon.

Also the sheer amount of variety is charming. It was an early jump to a massively more complex kind of hardware yet we see a ton of enemy variety (even for one off fights), a ton of weapons and customisable materia, a ton of sidequests, two optional companions, wildly different towns, and a whole underwater section.