hey this is a good poll....
I'd say the weakest faction is the Rebel Alliance, even though i like to play them, they are the weakest.
My reasons for thinking that are because, they don't have a jetpacker, and i think the wookiee is fairly useless.
I like being CIS and they they are fairly strong, with the Super Battle Droid, and the Droidika is a really good unit to be (if you know how to use it)
But overall... yes they are nicely balanced, besides the special units, the regular infantry is all the same.