Right now, I know Energi, the most profitable masternode service. A very high rate of 40%. But to set up a masternode, you have to have 10,000 NRG. That's an investment of about $ 30,000. I don't know if I'd have that much money.
In addition, altcoins like Qtum and Zcoin also offer masternodes. Although they do not offer as high profit rates as energy but I think they are worth exploring.