If HasTak ever run out of ideas, Hearts of Steel would be a great concept to explore. Off the top of my head, I can already think on at least 5 Bumblebee toys that turn into yellow mini-cars (and there's probably more); but I don't think there's ever been a Bumblebee toy that turns into a Victorian/Industrial Revolution era train.
Also, I know we've had loads of Starscreams (and seekers!), and people probably roll their eyes every time another one is announced.. But you can't deny that this is awesome!
There's no challenge here. I hate the movies! Therefore I hate ALL the transformers that appear in them! And they ALL look like ugly insects to me!
JUST KIDDING (everybody calm down)
Thinking about it more seriously... I thought DOTM Shockwave was pretty cool. It looked like G1 Shockwave (kinda sorta), and like G1 Shockwave; he was quite strong and menacing (enough to duel with Optimus), and he seemed like an evil engineer/mad scientist type (assuming he built the giant millipede thing that destroyed the buildings). But to be honest, his appearance felt more like a cameo because he was barely in it (less than 5 minutes, including the fight scenes), and he only had one line in the whole film (just one word actually, "Optimussss").