This is my personal opinion. I chose the merc and vanguard route, and am regreting it. Here is why.
Merc/Commando. Their dps tree, is spent standing in one place place, casting. This in my opinion makes more sense as a commando. Because, you have that giant assault canon, wich naturaly, would weigh you down. Jango/Boba, were very mobile. And the merc, is wielding two pistols. Also, most of your abilitys as a merc, (the ones used in this tree) are cast from the wrist. The commando, shoots all from the assault canon. So I think commando should be the route you choose.
Powertech/Vanguard. This class, is spent up close and personal. The vanguard is wielding a large assault rifle, and a powertech uses a little pistol. Doesn't it make a little sense to go toe to toe with someone with a small pistol, using one arm, for more mobility, vs the vanguards large clunky assault rifle? And is you go tanking, launching yourself at a target using a jetpack looks alot cooler then the vanguards sprint up to someone.
This is my opinion. Good luck on the choices. And, very sorry for the terrible spelling.
hehe, you nailed it perfectly man, i started with vanguard then dropped it for a PT + Commando. It's the only way to play Trooper/BH in this game. The mirrors are terrible. Vanguard has hands down the worst class animations in the game.