Recommended malware/virus scanner for mac?
I would recommend MalwareBytes. However, macOS already includes XProtect, which is a regularly updated blacklist of malware. On top of that, there are lots of built-in security features that make it very difficult for malware to do damage: processes are limited in what they can read or write.
Of course, I'm not suggesting that 'Macs don't get malware'. But if you're already cautious about downloading 'trashy software', then that's as effective as anything.
What you didn’t ask is are there products more effective than one that just tries to catch up with known malware. There’s a class of products that scan for suspicious behavior so you can decide if a program is worth the risk or be alerted to an uncatalogued risk. Start with Objective See products in that case.

https://objective-see.com/products/blockblock.html

LuLu and KnockKnock are worth looking at as well as the linked BlockBlock app from above.