What's the best tool for viral signup contests / waiting lists?

Looking for good bang for the buck, and not terribly concerned about integrations, but Wordpress would be nice.
Derek ShanahanGM @ SuperRewards · Asked

2 recommended

Maître Viral Referral Waiting List

Create a viral waiting list in 60 seconds

Emily Hodgins5Community and Marketing, Product Hunt · Written
Maître have a few different products from waiting lists, to contest platforms that could suit your needs here. I've not personally used them yet but have heard good things and they keep releasing updates. Worth checking out.
Viral Loops

Jordan SchauFounder, Pure Cycles · Written
Super easy to set up and very clean UI