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?
I always preferred a dark color - black or dark (olive)green are the common colors on the market. Mainly I do not like like white net bags as they reflect a lot of sunlight and my eyes are far too sensitive to the bright reflections. It would always give me spots for my eyes for a couple of minutes, making it hard to see the next interesting specimen clearly. Hard to see a specimen inside the net bag well for the same reason. Also white stands out a lot more in nature and I never liked to attract human attention while collecting. The darker color work the other way around on me. Easy to see the specimen and how perfect it is, before pinching it. Once you go dark or black, there's no going back....