Well, the cost is the main factor.
I have used multilogin and incognition, camelio before.
1. Multilogin is too costly, and is not great to scale, since it has limited account number per plan.
2. Incognition is not frequently updated.
3. Camelio gets caught and is not as great to be honest.
I do not think these anti-detect browsers are that complicated to make. (Except for multilogin with webgl and graphics card manipulation, I don't know how they pulled that off.)
They use different profiles, cookies, useragents, ips, and some cases, graphics, but if you use a common graphics card, that is hard to detect.