Is there truly a leader among ppd?

Do any really pay out better than another or have better conversions?
I'm currently using clean files because I require payment by check and weekly payments. Any thing better?

You could start your own and be the best. They're incredibly simple business models. If I had the tech know-how, I'd be all over that.

OP: You are at right place! "Clean Files" is the one who pays out better than other PPD networks. About checks, I think if you speak with the admin, may be they find a way out, for you!

Good luck!

Edit: There conversions are better than many other PPD and even CPA networks, BTW! (If we are speaking about content locking)

I use both from them. And they already offer check do that's good. So far I've experienced a great conversion rate.