Prolific Academic is a great site on which you complete surveys for cash. I really love this site because they have high paying studies and they are much more interesting than most. this is probably because they are being conducted by Academic Researchers. Most studies have gone through rigorous ethical approval via University Ethics Committees and are well-written. Sometimes it’s obvious that perhaps you’re completing a study for a less academically gifted researcher shall we say, as it’s been poorly thought out. Or occasionally the spelling and grammar is off, but I feel I can forgive that of people for whom English is not their first language.
Almost every study I’ve encountered on this site has paid at an equivalent to the minimum wage per hour of my time which automatically puts it above other survey sites. I personally wait until I’ve reached £20 to cash out, so I don’t have to pay additional Paypal fees. But you can cash out at any point from £5 onwards. Another great thing about this site is how quickly they pay out- sometimes in minutes!
From time-to-time the site seems to run slowly, possibly due to volume of traffic? I once found it kept telling me I had no surveys and it turned out my account had been flagged for no reason. I contacted them and they sorted it out very quickly. I highly recommend this site for higher paying, interesting survey opportunities.