If you can put up with the techie way that Onyx works, and you can hold out until it becomes available on Big Sur, then I see no real big reason to spend money on CleanMyMac.

On the other hand, CleanMyMac does one thing quite well that Onyx doesn’t do, and that is to clean out your personal Preferences with files that didn’t get properly removed by simply dropping an app into the trash. But even that may not be worth $39 for the dozen or so files lingering in Preferences that only take up a little space in the hard drive.

I do rely on CleanMyMac to completely uninstall an app. It’s more thorough than the free version of AppCleaner. CleanMyMac also cleans out hidden malware, viruses, and adware, and that’s something Onyx doesn’t do.

On the other hand, Onyx can rebuild certain Apple databases. I don’t think CleanMyMac does that.

So in the end, I think you need both. My approach to solve problems is CleanMyMac first followed by Onyx followed by a NVRAM/PRAM reset and then maybe even an SMC reset. In most cases, a corrupt Preferences file is the cause of an app not working right, and CleanMyMac handles that easily.

Here’s the thing with CleanMyMac. A single license can only be run on one computer - at a time. This means if you want to use it on several computers, you just need to reset the activation and activate it on a different computer - while your activation key is valid. I have one license and two computers that I use CleanMyMac on - just not activated on more than one at the same time.

Here is a comparison of Onyx and CleanMyMac

:https://macpaw.com/cleanmymac/cleanmymac-vs-onyx

John R Carter Sr