Any other opinions/thoughts on the matter? I'm really having a difficult time deciding!
I would go with Vanguard Mercenary. Dual Pistols really fit the Bounty Hunter (especially as a Pyrotech - Arsenal uses them far too little for my taste), while the Assault Cannon of the Commando is so large, clunky, unwieldy that I would never play one myself. Have a look at some fellow Commando players ingame, these impossibly huge blocky pieces on their back - some (the more elegant ones) may look right when drawn, but on their back it looks just... impossible, like they should fall over backwards any moment, or fall off their speeder bikes.
On the other hand, a Vanguard with a blaster rifle looks just right, just the way I would expect a Republic Trooper.