First and foremost, whatever is on sale because it's usually what no one else wants. Fine for me.

Given a choice, I like a brightly colored shelter so I can find it and because it looks more cheerful inside. I try to avoid the paramilitary look. I get enough of that at work.

For clothing, light colors to reflect the sun in the summer, dark colors to absorb the sun in the winter.

I like black for a sleeping bag because it seems to absorb heat and dry out faster in the sun. No science behind this, just my observation.