Other than the two most obvious weapons (the HK21 and RPK), the AUG and the Commando are both very good weapons to upgrade. Like the two LMGs, the AUG will be better without Double Tap, whereas the Commando will benefit greatly from it. I find the AUG's scope to be irritating at times, however, and it has gotten me downed on occasion since it makes me lose my peripheral vision.