I wouldn't mind seeing a Shockwave based on the comic incarnation - a thinker who goes into the situation with a plan. Perhaps with the intent of taking advantage of Optimus's message at the end of the first film to establish an ambush on Earth for Autobot forces that are responding to Prime's rallying cry.
The fighter junkie in me would quite like to see Jetfire in the next film - and the idea of him debuting as a Decepticon and perhaps shifting sides in the last reel would work quite well. It would also give us a good excuse for a really good knock-down-drag-out aerial battle for the sequel.
On a personal note I would love for a bit more objective camera in the battle sequences. I'm not sure that the audience always needs to be a participant in the battle sequence to be wowed by it. I'd argue you can still do some very good set pieces with objective camera.
No humans other than Megan (we're on first name basis, me and Megs...)
For me, deffs are: Shockwave -liking Legios's ambush idea. Prowl -what do you expect me to say? Grimlock -I think there could be conflict between him and Prowl as well as him and Prime. Wheeljack -FIXES JAAAAZZZZ!!! And of course, Soundwave -in a super-cool new alt mode, spy plane maybe.
One thing I would like to see is a shed load of CYBERTRON! I think they need to really make the sequel different, shake it up, unballance us, don't do the usual "sequel thing" where it's more or less a re-telling of the first film as a ship to show off more, amazing as they were, robot fight scenes. Maybe, Shockwave ambuses the Autobots on Earth as Soundwave secretly rescues Megatron. Optimus has to run to Cybertron for some reason and takes Sam and ol' Foxy with him. I dunno... I'm rammbeling now...
I was the one who let you know, I was your sorry ever after, '84, '85. Give me new toys and I'll decide, but I'm really only after, '84, '85.
I actually have no wishes for the second film. Like the IDW comics, the film versions of Transformers are new takes on the concept rather than adaptations of older material. Therefore I feel even if I say "I want character x", there's no way to say what they would be like in the film. Even if you just say 'Shockwave', for some folk that means the cartoon version, who is a completely different character from the comic version, and so on.
"I used to think it was a terrible thing that life was so unfair. Then I thought, 'what if life were fair, and all of the terrible things that happen to us came because we really deserved them?' Now I take great comfort in the general unfairness and hostility of the universe." — Marcus Cole, Babylon 5 — A Late Delivery from Avalon
I've thought about it...It's a hard one, because It's likely we'll get Arcee, and probably Prowl will replace Jazz if he isn't repaired in some crazy way.
In my heart, i just don't see the point of choosing the characters i love if they aren't going to get much screen-time or dialogue. However i think a lot of the human-based backstory wont be nescessary in the sequel.
If i'm being honest, i don't want any new characters just now, i want the current characters to get a little more definition first.
THEN we can have Dinobots vs Devestator for the 3rd film!