Not a big fan of Kingdom Hearts. Well, if the battle system needs you to press more than one button it's gonna be a big improvement.
Every FF game only requires 1 button in combat lol.
FF15 plays like Kingdom Hearts where the combat is in real time, but you will need to heal, cast spells, warp (warp is new to the system, you can only warp to where you throw your sword), and summons. It's certainly not a hack and slash, it's just real time instead of turn based and looks fast. If more buttons = better combat for you (more interaction/control I assume you mean) then it'll certainly be the best FF game on the gameplay front.
I think if people let go of the old school mentality where combat needs to be slow and tactical in FF games, you can see the game for what it is which is a fast paced tactical battle system that still has the whole magic/summon/party system, just much more fluid and action based. Plus, bringing back the open world/vehicles/dungeons and adding things like a day/night cycle make it very interesting.