This is a tough one to answer. A Stormtrooper rarely hits their target (according to some), but a Red Shirt always seems to die. However, Red Shirts aren’t known for missing shots, just getting killed all the time.
Yet, as a Stormtrooper I’m serving a corrupt, fascist empire. As a Red Shirt I’m serving a democratic Federation. Yet logic would tell me to choose Stormtrooper and quickly defect as the survival rate might be higher. But then I would most likely live life on the run.
My answer would be: Redshirt. I would probably be able to borrow or steal someone’s colored shirt that is different, and possibly survive, or avoid the away mission all together.
I’d have to go with red shirt as well. While the chances of death on an away mission are high, it is not guaranteed. And I’d rather spend what time I have exploring strange new worlds than serving Palpatine and his evil empire.