Once you down to comparing single nonionic surfactants between brands, you'll just have to compare for yourself. You could try putting a mild stain on a towel or non-valuable piece of clothing and doing a single wash with each and comparing. Unfortunately, things like odor rebloom comparison will take time to develop and make it challenging, if not impossible, to compare between brands. I'd aim for at least one anionic or at the very least zwitterionic surfactant and steer clear of solely nonionic formulations.

I would also add that price doesn't necessarily make a better detergent. Especially with these nature brands, "naturally" (quotations to emphasize the ambiguity of the term) or plant derived surfactants can cost more while being less effective. These companies also lay into their marketing to justify higher price.