The table above showcases the slot games that offer the highest percentage of payout. READ MORE: Best Online Casinos for Beginners RTP Percentage Explained We ranked slots by Return to Player percentage, which we'll explain more below. Research does show that there are slot machines that offer gamers a better shot at winning than others. Every online gamer will have an opinion about which slots are superior, but this is based on more of a gut feeling and superstition.