After too many years of pondering this question - I decided that it doesn't matter that much. It's the air resistance I think about when I buy. I'm looking for a net bag that slices through the air with no resistance at the end of a fully extended extension net.
That said - As I've gotten older, I have a hard time seeing small bugs in a dark bag, so I'm more likely to screw them up in handling.
White one is definitely too visible for unwanted eye near you. I’d say khaki colour is the best, I don’t know about insects but for sure for public. Also bamboo stick works best in this case as a combo.
I always use black as I find it's the best colour to allow you to examine what's inside it, and it doesn't attract as much attention as some other colours. However, some colours will attract some groups, e.g. white for Parnassius, red for Ornithoptera, blue for Morpho, P. Ulysses etc.
It seems to me that camouflage would work well because it would blend into the background and the butterflies wouldn't be scared off. I've never tried camo, nor have I seen camo nets for sale. Has anybody else used one?