I rather enjoy Software's look, thanks to stuff such as the signature Doom light fade out, and as a mapper and texture artist it's a lot more fun experimenting and looking at palette effects and colormaps than always truecolor and lame looking fog (see: Groggy Gale).
Though, I gotta admit that perspective correction's such a nice boon, and I'll often use it when I connect to a Match/CTF server (in those modes colormaps just make it harder to play anyhow, though really that's the map's fault; please stop colormapping match/ctf maps :U). My ideal renderer would be OpenGL with a palette shader, like GZDoom has gotten recently.