The 3rd nominee is Jazz. He's a pretty good choice, and I'm thinking that he might be the only 1984 Autobot car character to choose from. Which I won't; as stated, Soundwave gets my vote.
Oh, and I decided to open Recon Ravage last night. I'm glad I did; he actually does look pretty awesome in hand and also quite different from the original version. Also (and I don't know why it took me so long to think of this), but I finally made fictional sense of him, too - he's ravage after being rebuilt following his death at the hands of Bumblebee. Sure, he doesn't look like this in the post-ROTF comics (where he has been resurrected), but the vaguely-patchwork look he has really sells the "rebuilt without a new paint job" idea I've got.