I assume you're talking about the movie Starship Troopers
Because if its book Mobile Infantry vs. Aliens Colonial Marines, it'd be a landslide vicotory for the Mobile Infantry.
if you're referring to the movies, Colonial Marines by far. Lets look at the women in the forces. WHO WOULD WIN:
PFC Jeanette "Ever Been Mistaken for a Man?" Vasquez

vs.
PVT Dizzy "Whoops i forgot to exfoliate before fighting bugs" Flores

furthermore, lets look at how the two of them died:
Vasquez honorably blew herself up to facilitate the escape of others
Dizzy turned her back on the enemy and got fucking arm-barb pwned, dying like a bitch in her lover's arm.
its clear enough to me, need more be said?
I think a better discussion would be who, if it were Aliens vs Klendathu bugs, would win, if each controlled half a planet. But thats just me