I like:
Warp Talons because they look cool.
The Orks that wear rockets because they look cool.
Snikrot because his rules are cool.
Deamon Princes because they look cool.
The Death Jester because he looks cool.
Wytches cause they kill stuff good?
Necron flyers because they look cool.
Trygons because ROAR!
Arjac Rockfist cause he's clearly a BAMF.
Blood Crushers because Blood Crushers.
The ForgeWorld Bloodthirster Greater Deamon of Khorne because IT'S CLOBBERING TIME!