I don't know about drop-in Ubuntu replacements because I don't think I've
ever installed Ubuntu without regretting it. But I've been using MX Linux
for several years now, and it works very well. It's pretty much straight
Debian, but with multimedia and some other stuff. I install the XFCE
version, then install TDE. Install is pretty painless, especially if you
keep your home directory, which is a lot easier if you use a separate /home
partition. The one thing I don't like is usually having to reinstall when
it changes to a new Debian version, but I haven't yet found a rolling
release that can use TDE.