This is sad, Fedora has been my favourite distribution for a little while. Red Hat have been a good community player and it is a big loss for them to be gobbled up by IBM. What is the best alternative to Fedora and CentOS?
The obvious alternative would be Ubuntu. The LTS releases are alternatives to RHEL/CentOS. The others are Fedora alternatives.
However, Red Hat is _far_ more than RHEL. They actually build a ton of OSS that's used in RHEL and elsewhere. Ubuntu does little more than repackage Debian. That's not a criticism. They package well, and they know how to polish. But there's no replacement for Red Hat as a company.
Try vanilla Debian. I really don't get the fascination with Ubuntu - modern Debian does all the same things, and in many cases it does it better (saner defaults, less opinionated).
And if one really needs a "one click out of the box" desktop distro, then Mint.
LMDE has been around for several years now. IMO, it's "experimental" in the same way many Google services are "beta". Which is to say, in practice, it works just fine.