Hmm, I actually did a video a while back on MX Linux. It's pretty good, and a lot of people talk about it.

About the MP3's issue. The reason why Ubuntu can't play them or many other formats is because of licensing. There is software in Linux with licenses that restrict distributing that software with other software that uses incompatible licenses, and proprietary/non-free codecs like .mp3 is one of those.
So they can make it available to you, but they can't package it with the OS itself.
I'm thinking that with Linux Mint/MX-Linux they have the option to "Install Extras Such as .mp3 codecs" somewhere during the installation. Pretty sure Ubuntu does this too now, but before they didn't.