off the top of my head, merely by the way they sound.
good ones...
dr. octopus
dr. fate
dr. doom
dr. strange ( i guess "dr." just makes names sound better. it sure did for octopus...)
apocalypse
thanos
silver surfer
fallen One
colossus
wraith
fire lord
chaos
galactus is cool, imo
carnivore
venom
quicksilver
onslaught
asteroth
sauron
ronan
deadpool
deathstroke
bad ones...
hulk
strong guy
the spot
the shocker
catman
catwoman ( i actually love cats)
beta ray bill
honestly... batman is a dumb ass sounding name
mr. fantastic is a fantastically awful name
Gog
good and bad...
squirrel girl