Battlefront
No just stock Doom 3, I've never tried any mods for it.
I got the vanilla one too, no mods but they "patched" that in years ago. I bought it some two years ago and didn't rememember it being differently when playing the demo for it back in the day. The original is either gun or flashlight..which makes it even more freaky to play.
Doom 2 (and 1): agreed, play them every other month. You ever tried Dark Forces though? I believe it came shortly after Doom2 and while not quite there it's super enjoyable if one isn't bothered by outdated graphics. Top notch level design (!!) - I'd say more or less on par with the Doom ones. And up until now (6 missions in) every single level was vastly different - including textures. Very impressed with that game - too bad I couldn't play it back in 1996 or whenever it got released.