As a primarily rebel player who is just now getting into Imperials, I will say this. Imperial Commanders suck. There is almost no bad choice in the entirety of the Rebel options, but on the Imperial side really the cost effective options seem to be Motti and Jerjerrod. Everyone else is just kind of inferior to the Rebel Commanders.
Ok, fine, Cracken and Garm aren't great (I actually forgot Cracken existed), and Jerjerrod is FANTASTIC, so maybe things are moving in the right direction.