Is UHRS on Appen better than Clickworker?

I was thinking of starting UHRS work and I've heard with Appen its possible that you get more hits or ones specifically for Appen that don't show on clickworker. Does anyone know if this is true or if its worth it to go through Appen rather than clickworker? The only reason I really didn't want to try Appen is because they mail you a check every month as method of payment.