It's hard to say. When it comes to FF4 I've played most of the different versions except for the 3D one. I really like the original look and OST of the original SNES release (I usually play the Japanese version with a translation patch) but I also like the other versions with extra content (the GBA version I play with the original OST patched in though - don't like the new OST).

When it comes to FF1 I've never given the NES version a proper go because I don't like the attacks not re-assigning automatically. But again I've played a lot of the different remakes (PSX, GBA, PSP etc).

I think it would be dependent on the entry in question. I'm guessing though that for a more drastic re-imagining of one of the games like the FF7 remake nothing will beat the original for me.