Hmmmm tough i wanna say the bug but i love bb's power output. Toss up
Supermex
BB to vers for the Bug
Magog
I think the only chance Annihilus would have is if he was able to mind control Hank Pym into shrinking BB down to the size of a dust mite...even then he'd probably still have to wear some ear plugs if he wanted to get close enough to squash him.