Well if you are going to start looking for a first panel, gather all info you can, find the most popular ones and find out how old they are actually. I found 2 panels that are originating from 2013-14, but some services costs more than on some panels from 2016 for example which doesn't make any sense, which suggest me that those newer panels use different provider, which also doesn't make sense but hey, who knows. It's really hard to follow all that and i doubt we will ever find out.
Probably of all those panels only 1 or 2 have a real supplier or they are have their account bot farms.