Honestly I don't like the idea of any of the 2D final fantasy games getting a remake. A pixel perfect upgrade maybe. All the prior remakes of those games have been pretty garbage. I did not like the FFIV remake, it sucks.
As for the 3D ones, FFVII is still up in the air as to being a good remake, but for what it's worth it seems like the best candidate for one. The others getting a remaster seems good enough for me. Id rather they focus on getting back to their roots and creating better NEW final fantasy games. FFXIII and FFXV were not the best, I owe part of the to the focus on the focus on action vs turn based, but at the very least work needs to be done to bring FF back to glory of being the mainstay it was.