I am a member of few user testing sites and can say with certainty UserTesting is one of the best. Not only do they have a high number of tests, but their user support is top notch. I definitely say they have far more opportunities to test than most of the other well known sites. They don’t pre-match you, so you do normally need to answer a couple of questions to see if you are eligible. However, I would say their high availability of tests makes up for the fact you may not be eligible for all of them. Honestly, I would highly recommend if you want to get into user testing. It’s a great company for new and experienced testers and the range of companies/websites etc that you are testing is great for getting more experience and having fun! They pay out exactly 7 days after you submit the test, so it means it’s really easy to keep track of when you will be paid. There is also a page on your account that shows all the dates and times of submitted tests, so if you are unsure of when you are due to be paid, it’s so easy to just log on and see.