I was always the most impressed by the SNES version. I know that as far as playing, there are far better choices such as PC, Jag, or PS1, but it's really cool how they could get DOOM on a 16-bit console. That's not the only game that showed the prowess of the SNES and its flexible, expandable hardware.
I share this sentiment completely. SNES Doom is not the best version of Doom, but I love it and still come back to it routinely. It's just something about it running on a SNES that makes it better than it is.