ALWAYS - I either don't like to or can't put the crosshair on a target to shoot, and autoaim makes me feel powerful!
SOMETIMES - If it's subtle and done right, it can really help the game be fun!
SELDOM - It's rare that I want the aiming challenge taken away from me, but sometimes it can be ok.
NEVER - Autoaim is for weaklings.
OTHER - My opinion is not listed, so I'll post a comment.