For me there's a little bit hard in mining because we dont know whether the sites are paying, but I saw also more people earning in many sites. I hope there's a sure mining already and no scam site.
They are many legit out there so better to try coinmarket cap to choose if what altcoin is the best try to choose you want the top 20 coinmarketcap they are many altcoin that you can mine with gpu mining rig..