Favorite line is Classics/Universe, so I guess the one from that line I would destroy would be..... the little helicopter minicon dude.
Nah, that's kinda cheating. EVERYONE hates that dude. I guess if I had to pick a larger figure, I would say Universe Dropshot (the yellow Scattershot repaint). What a waste of a figure. I only own him for the sake of completeness.
From the other lines, just for the hell of it:
G1: Ruckus... he's the only Triggercon I have, and he does nothing for me. He's hidden in the back of my shelves anyway.
Movie: Blazemaster, a terrible mold
Animated: this is harder, 'cause it's a small line without many useless fillers.... I guess I would say Activators Patrol Bumblebee
AEC: Cybertron Runamuck.... no surprise there
G2: Electro.... if his GPS doesn't destroy him first
Titaniums: G.I. Joe Megatron, of course
RiD: eh, already sold all the ones I didn't like... but it would have been Sideways, the black and yellow motorcycle. I HATE that mold.
Masterpiece: touch choice, but I think DVD Prime is the weakest link
Alt/BT: Battle Ravage