I’ve spent some time with the first three, so I can give my opinion on those.
The FF1 remake is very different experience than the NES original. That version had a ton of minor bugs that gave that gave it a unique balance. Every subsequent remake, including the pixel remaster, has been an attempt to fix those bugs, and add modem QoL features, and then rebalance the game to try to keep the same feel. I think the pixel remaster is a good game, and comes closer to the feel of the original than some other remakes, but it is still a distinctly different experience. I’d characterize it as a different game wearing the same clothes.
The FF2 remaster, on the other hand, is probably the best way to experience that game. The Famicom original is notoriously unbalanced and player-hostile, but those problems are effectively bypassed by the simple inclusion of two QoL features: a map, and a one-button autobattle. It took decades, but FF2 is finally worth recommending to more than hardcore fans.
The FF3 remaster is in an odd situation, in that this is the first time a close approximation of the Famicom original is officially available outside of Japan. The DS remake from 2006 is a significantly different game, especially in the first couple of hours. I didn’t play as much of this one as the other two, but I can’t imagine it deviates too much in the later parts of the game. I would guess, though, that the more flexible save mechanics make the notoriously difficult final three dungeons much more manageable, though maybe more prone to soft-locking.