1. r2- r2 has 4000 years better technology and anakin customized him(yes r2 is a him)
2.hk-47- his programming is superior to the hk-50's and he actually is still alive aorund 1.5
3.magna gaurd- they could keep up with jedi knights
4.ig-88- ig-88 would smoke oom-9 easily without difficulty.
5.i honestly dunno i wanna say the droideka becasue of their shielding.
6.GO-TO- he asctually has weapons where remotes aren't lethal.