I would want Stunticons (with combined Menasor), Slipstream (or Nightbird, who is technically not a TF but could be reworked into one for the live action films) and probably Waspinator and Blackarachnia/Airachnid, perhaps led by Nemesis Prime in a more intelligent form (than armada) for Decepticons.
For Autobots Id say Omega Supreme, Blurr, Rodimus, and
Ultra Magnus, and of course Moonracer (as some of you know I am a huge fan of Moonracer :<) Dinobots and Warpath.
With that roster I suppose since they like to copy G1 stories they could use a mix between "The Key to Vector Sigma" and "Enter the NIghtbird" with a story based on the idea that humans and autobots figured out a machine to make transformers from regular machines similar to the allspark eneregy in movie 1, but some evil humans steal the technology making the cons.
