If you are intent on making money, most people would tell you to stay away from casinos/slots in general, but this is not true. The problem being, you may burn through your money faster due to variance, despite the higher overall return. With that being said, you are MUCH better off firing $5 a spin on a $1 machine than betting $5 on a penny machine, as penny machines have the worst return of any game in the casino, and your money would technically last longer on a $5 denomination machine vs a $1 machine.
Higher denomination machines have a lower house edge (you get more of your money back per spin on average) with the tradeoff being you have to bet more on average. Do you just want to go with the intent of passing time, burning money, entertaining yourself and maybe have a chance at winning big? Then play whatever, there is no right or wrong, but you can use a bit of knowledge to try and stretch your money longer.
Contrary to popular belief, slots are very complicated and what you are going to play should depend on a lot of things, but most people don't bother asking themselves these questions.
