3DSen is an awesome emulator. I have no idea what black magic (yes, this is a nod to how the Koopas were originally known for their black magic instead of just being evil turtles) the makers used to make an NES emulator that actually turns the original NES ROM files into 3D models using voxels on the fly, but just the fact that it exists is awesome.
I honestly hate the gbc one. They could've done a better job and we have got better bootlegs like the super Mario World designed for the NES by Hummer team
OK. Let's take: - The musics of the NES version. - The colors and graphics of the SNES version. - The voice samples (I know, some don't like it, but I love it) of the GBA version but in a better quality. And then we would have the best SMB3 version of all times.