I'm a rebel main. Even though I love clones (particularly cause I love the Clone Wars series, and the Clones in that show), Rebels will continue to be my main because, other than having the playstyle I love, they're very easy to customize model-wise with bits and the like while still fitting into canon lore.
Anyways, with that in mind, I would LOVE to see DF.9 Laser Turret as a Stationary Heavy unit for the Rebels. I'd also really like to see Tauntaun Riders as a support for Rebels. Maybe as a 2 or 3 of squad?
For the Imperials, however, I'd like to see them get the Dewback Trooper as a support, and as for the heavy... not sure. Imperials have many heavies I'd like to see, but I think the TX-225 Occupier would be an interesting inclusion that most would recognize easily.
Now, as for the Clones and Separatists.... My step bro will be playing Separatists, he wants to do a'junkyard droids' theme, with various droid bits replacing parts of the droid bodies. Anywayssss I think having Grievous, a STAP Squad, and 2x B1 Battle Droid Squads up against Kenobi, an AT-RT, and 2x Clone Trooper squads would make for a good starter box for that era.