Most slot machines usually offer an incentive to play the maximum coins. For example two coins may pay 2,000 on the jackpot but three coins will pay 5,000. So if there an economy of scale incentive, then the return is higher with a max-coin bet. However, I should mention that most casinos tend to increase the theoretical return on their slots as they go up in denomination. So, you may be better off betting one coin on a $1 machine than four coins on a quarter machine.
My advice on slot selection is to play a simple smaller game. Nothing with fancy signage or a huge screen. Ultimately, it is the players that pay for that in the form of a lower return.