Okay this post is completely opinionated, and ill be glad to see your opinions. Your list doesn't have to refer only to the COG.
10- Kim: the only background given about him is RAAMs shadow, and its only that he helped evacuate Ilima. More could have been done to develop him a bit more. He had leadership qualities ect.
9- Valera. Its just like she took up a squad spot and that's it. The only good she did was indirectly enlist jace
8- Barrick- Yet another random person. Wasn't in 3, so some won't ever know what happened to him.
7- Skorge- the kantus "cult" I suppose came out of nowhere in 2, and wasn't really explained; as well as skorge. He was basically the GOW darth maul.
6- Sam- Yet another walk on character. She just seems like the character that adds to bairds antics and that's all
5- Tai- Had so much potential to be a bada**, but it was all wasted.
4- Jace- he seemed to do more complaining than fighting. But it is a step up from his kinda cameo in 2
3- Dizzy- yet again, wasted potential
2- RAAM- in my eyes the proper leader for the locust. Stern, cunning, merciless and kinda scary. He puts the queen and skorge to shame. Another shame is that he was killed off in 1.
1- Clay Carmine- they had a giant vote for him to live or die and he wasn't even in 3 for a substantial amount of time. His "dramatic" survival wasn't even had zero merit. Epic should have made him survive an ambush of like 40 locust by himself, not a heli crash.