Best paying slot machines are those that offer high return-to-player (RTP) percentages, typically above 95%. These games often feature exciting themes, engaging graphics, and bonus features that enhance the gaming experience. Popular titles like "Mega Moolah" and "Gonzo's Quest" are renowned for their lucrative payouts and progressive jackpots. Players should also consider volatility; high volatility slots may offer bigger wins but less frequently, while low volatility slots provide smaller, more consistent payouts. Researching and choosing the right machine can significantly increase the chances of a rewarding gaming session.