To me, my perfect Final Fantasy is one that are slow, methodical but also an absolute epic journey full of action, comedy, tragedy, love, hate, overcoming flaws and personal demons, meaningful reasons for an unlikely party to stick together, larger-than-life villains and defying fate.
The best kind of locations in Final Fantasy games are usually dense citadels full of people to talk or at least visually striking locations that unique shapes and wild colour pallets, putting emphasis that we're inside the mind of someone's fantasy as if it were to be... final. If the locations were to be more grounded in reality, it should still be as beautiful as possible, even if it's empty and ominous or low and gritty. Midgar, Alexandria, Lindblum, Zanarkand, Archades, Bodhum, Palumpolum, Eden, Academia, Luxerion, Altissia and, last but not least, Insomnia (when the city lights up the night sky). Worlds like these are a reason why I love art.
If we're ideal gameplay, perhaps turn-based combat uses the battlefield as a part of the fight e.g. Shoot the explosive tanker beside the enemy, throw the enemy onto the ceiling, take over from taking damage, use elemental magic to your advantage like ice or thunder while enemies are in water and so on, so forth. While summons would be essential, dynamic team combos like a chain-Limit-Break would be awesome along with shifting between classes on the fly when the fight gets tougher. For exploration, the overworld map with the character being bigger than the locations from I to IX is perfect and cost-effective than making the entire world big. Miles of grassy fields isn't really enough to get make engaged.
No composer is better than the rest because they're all perfect in their own way. Uematu's epic scores, Shimomura's work with the piano, Hamauzu's atmospheric electronics, it all depends on location, characters and theme. Maybe I lean more towards Hamauzu but that's because his music fits more trippy imagery.
Graphics? Make sure there's some floating crystals, the big ones in their crystal rooms and small shards floating in the air.
Gotta have gunblades, pretty boys, pretty girls, pretty everything else, libraries, magitek, airships, chocobo, Gilgamesh, B&B rooms to sleep in, Tetra Master, the awesome final boss designs and the main menu and cover art must have minimalistic white backgrounds like in the PS1 and PS2 days. Why is American cover art so ugly compared to European covers?
I want to my ideal Final Fantasy more coherently but that would take too long and I can't stay up all night.