Over the years I have used roe from all 5 pacific species for coho and they all work. I just use whatever I have the most of on hand and don't feel at a disadvantage. I do prefer some roe over other due to ease of curing and handling, but that's not related to fish catching ability.
Someone up thread mentioned extremely immature eggs may not cure as well which is a valid point, but generally I've found that all salmon roe if prepared properly will take coho.
One thing I've noticed it that some species roe are naturally lighter or darker than others. Chum roe usually starts out a quite bit paler than say coho roe, and can either be cured to very bright colors if one so desires, left natural, or anything in between. The same curing process can result in very different colours, so depending on what you like, you might come to prefer one species on that factor alone.
... since I have a wide range of species and egg sizes, I'll make sure I take notes on what works and what doesn't.
Overall I wouldnt sweat it. Whatever you have will work, and I'd actually be somewhat surprised/interested if you found a particular species of roe vastly outperformed the others, that couldn't be attributed to some other factor like colour, cure quality, etc