When it comes to the best online slot machines, there are a few things that you need to look out for. The first thing is the quality of the graphics. If the graphics are not good, then you're not going to enjoy playing the game. The second thing is the theme of the game. Make sure that you choose a game that has a theme that you enjoy. The third thing is the bonus rounds. Make sure that the bonus rounds are exciting and offer a lot of value. Finally, make sure that the casino is reputable and has a good reputation.