Rack n Ruin comes to mind. We've gotten several Impactors, and Xaaron even got a nod as Ruination's head, but we've never gotten these guys.
Macabre...because Squadron X deserves at least a little of the love that the Wreckers have been getting.
Megadeath could make a pretty neat new Pretender.
Rorza the Rocket-Cycle Racer from Rigel III. Because...c'mon that name alone.
Deathbringer...again, mostly because of that name. Not sure if I'd want a G1 or IDW1 version, so...maybe some combination of both? You might be able to make one form transform into another, like Ninjor from Power Rangers.
Tarn, although we're getting statues and action figures, but no transforming toys. Or we could go with Kaon, Tesarus, or Nickel, just to cover more ground. All of them have unique designs.
Nova Prime. We technically got a toy of this, but I want one with the wings and everything.
Buster, Thundercracker's dog, because...she's just such a good girl! She'd be fun as a plush or a pack-in "accessory" with a version of Thundercracker.
Velocity. I don't know, she has a neat design.
Pharma, again, he's got a neat design.
Tyrest...again, a neat design.
Centurion aka Hearts of Steel Bumblebee. Hey, why not most of the Hearts of Steel cast (including their prehistoric forms!)
A Onyx Prime/Shockwave Pretender would have been pretty neat.
Yoketron from Animated.
Scowl from RID15. An Ankylosaurus Decepticon with a neat design.
Star Upper. I'm not sure they could really DO a boxing kangaroo anymore (animal cruelty concerns). Still, it'd be neat.
Crow Convoy from Beast Wars Neo...just because I want someone to try and make a toy of out him.
Violen Jiger/Violengiguar/Vincent. He'd just make a really cool toy.
Dark Nova. Getting Super Megatron makes this a non-zero possibility, right?
Citadel Secundus from Rescue Bots Academy has a neat color scheme.
Paddles...because someone has to remember Paddles.
G1 Cartoon "Sentinel Prime"...because a rhinoceros truck is kind of a cool alt-mode.
And most of the Thirteen. Unless you count the Prime Masters. But I mean...I don't, so...