I just like mowing down zombiedudes, I'm vanilla like that.
The flying skulls (lost souls?) are kinda boring to fight I think.
DOOM
Zombies are a great pick, more meat for the grinder.
I hate lost souls so much! Infinite sadness when I die to them.
Cacodemons always scare the shit out of me
I like the sound Barons of Hell make when they die. Finally killing them is satisfying. I also appreciate the audio cue for Lost Souls, although fighting them is less than pleasant.
I just encountered my first Arch-vile in Doom II and yup, I hate them as much as it seems everyone else does. I won't be offended if y'all give me tips.
I think my favorite enemy, both design and combat wise, is the Revenant. It's an enemy that immediately demands attention, both through it's scream and with it's absurdly dangerous guided missiles. But it's also a bit squishy so you cn take it out quickly if you get the drop on them. Plus, an angry skeleton with cybernetic armor and missile launchers is really cool.