I'm a Prizerebel member. It's a great site known for it's fast prize shipping time. They have pretty decent offers, but as a referrer, I really didn't like the 1-tier referral system. Plus, you don't get any bonuses for actives or signups. I've made so much points over the 4 years I've used Prizerebel, so I don't see myself quitting any time soon.
The reason I use Prizerebel over cash sites is because when you say "free nintendo points/MSP/itunes sent straight to your e-mail no credit cards or personal info required", it sounds a lot more legit than "free money". In other words, the points system has a niche that I can use, whereas I have no idea where to run my referring campaign for a cash site.
Still, I'm looking into using Fusioncash as my primary referring GPT site because it has the best referral system I've ever seen.