Okay. There's a difference between a Desktop Environment and a Window Manager. There are lots of Window Managers, but not that many DEs. Ive played around with a lot of them, and I thought I'd share my thoughts:
- Gnome my #1 since 3 hit, this is my home and where I always end up. It might be lacking in configuration options, but it's got a great look, coherent design, and a default workflow that feels like it was designed specifically for me.
- KDE Plasma Desktop is massively configurable, to an almost shocking degree. There's very little you can't do with Plasma. It's perhaps a bit less stable than Gnome, and you can break it depending on your settings choices, but holy crow, it's amazing.
- XFCE is my go to for older computers. It's light, fast, and has a lot of configuration options. You can get it looking pretty cool with some work. It's missing some of the fancier features, and development is slow, but that's by design. It's super stable. I kind of think of it as the Debian of DEs.
- LXQT even lighter than XFCE, but based on QT rather than GTK3. It's fine, but I think the GUI tools are kinda ugly.
- Cinnamon was originally a Gnome 3 fork. It's fine I guess, if you want your desktop to use the Windows workflow. Nemo is an excellent file manager, and there are a lot of fun ways to configure the look, but I just don't care for it.
- Pantheon is the official DE of elementary OS. It's pretty in a Apple sort of way, but it's tools felt a little dated and the theming outside of the official elementary apps was inconsistent at best. It want to like it, but it feels incomplete.
- Deepin has a similar problem - it's own apps look great, other apps look like they're from another planet. It's got a really nice look, though, and a good kinda feel to it.
- CDE the Common Desktop Environment. I tried it as a goof. It's... well, let's say it's nostalgic. It's been around for 30 years, and started out as a Unix desktop. It still looks pretty close to where it started, but it's up to date (the last stable release was like October last year I think). It's zippy of you can put up with the designed-for-EGA color palette, but really only good for a lark.
Hopping around to different DEs can be fun, but at the end of the day, the trick is to find one that has a workflow that works for you, or use KDE and make the workflow you need.
ETA: Somehow, I forgot to mention Mate. Basically, it's an updated version of Gnome 2, which, to me, is an uglier and more awkward to configure XFCE. It's not for me, but a lot of folks really love it. It's so cool that we have a choice, and can be different!