Deathmask was good, until the proper doom style games started to appear. Good in deathmatch 2 player split screen, if I remember it was kind of like eye of the beholder movement but you moved in half-squares, which made it a bit smoother.
Alien Breed 3D and Gloom were my 2 favourites, AB3D because it was the closest you could get to Doom on the amiga, and had some nice touches you didnt get in Doom, like the grenade launcher you could rain death from the skies with, platforms above platforms, transparant water and 3D polygon enemies (well, one, the robot on level 8 was in 3D i think). Gloom was good because there was nothing like it on the PC, was pure arcade style fast and furious action, and I don't think there had been a doom clone on any platform which had a split screen 2 player mode when this came out (or had there?).
AB3D 2 was ok, just terribly slow and the enemies were crap (the lanky blue and green stick insect things, what were they all about), as were the weapons (the grenade launcher pitifully rolled grenades out about 2 feet in front of you, nice), oh and had stupid levels in which you had to traverse mainly lava to collect the keys. Breathless was ok for a while, but pretty repetitive.
Fears was probably the worst doom clone ever, on any platform. Enemies that homed in directly on the player, walking into walls, constantly firing, with no AI whatsoever. The most clumsy controls you can imagine. And a 2 player link up option, with 3 levels (all the same level, but with different wall textures) and a shotgun which takes precisely 99 hits to kill the other player. But the level editor was ok.
