The network I'm part of is ScaleLab.
I've been with them since the beginning of the year, and have found them to be really very good. They respond to emails in person, promptly, and don't have a lock-in contract. I'm at liberty to leave on only a month's notice. A real bonus for me is that they pay out via Paypal. That's a win for me. And I never, ever received any spam from them before I joined! I was referred to them by another atheist channel, and am glad to be part of it.
If you're a Youtuber and you're looking to join a network, I happily recommend ScaleLab.