When I was posting a rental ad for my SFH, I quickly realized how powerful Facebook Marketplace and Craigslist are. The calls couldn't stop after posting there.
I have only used zillow and Craigslist and that has given us more calls and tenants than we usually know what to do with. The key is quality photos and/or videos and attractive descriptions! Good luck!
The best platforms to post your rental ads are with software that syndicates it to a large quantity of listing sites. The more eyes on your listing, the better. The main ones to focus on are Zillow, Trulia, Hotpads, Rent.com, and Craigslist. However, there are many smaller listing sites I've seen many renters find listings on, but that most landlords haven't really thought about before posting on before. That's why I recommend searching for a software that you upload all of your property information on and it will take care of the marketing to all of those listing sites; big and small.
Please feel free to reach out to me if you need any suggestions!