Personally, I’m not the biggest fan of Debian’s and by extension Ubuntu’s development and distribution model. That being said, it’s my personal preference, and not an objective judgement on quality.
Mint doesn’t really have any features that make it especially interesting for advanced users that it doesn’t inherit from Ubuntu or by extension Debian. Or does it?
Again, not trying to shit on it or anything, but Mint’s goal was always to create an easy distribution, which is no small feat. But this is nothing I’d associate with “advanced users”.
Don’t think of Mint as an “easy distro”, but rather as a distro that tries to stay the hell out of your way as much as possible to get things done. Any OS - Linux, Windows, Mac, BSD, or Unix is merely the means to the end goal of the user and not the reason itself. I don’t want an interesting or complex distro. I want a distro that helps me to do a task.
You want something interesting? Give LFS, (Linux from Scratch), a try. That’s an advanced distro that you can make as interesting as you desire.