My opinion on the desktops:
I personally prefer something like KDE because it has a million tools and a few of them is really good.
But it is developed by people who likes to implement a cool new feature and fixing bugs is not always as fun.
This means most of the things work in the way they were intended to be used, but if you push the boundaries a bit, they might stop to work.
Go for KDE if you want features.
Gnome has the opposite approach.
They go for the visual appealing desktop and if something has a bug in it, they either claim it is a feature or remove the feature just to make people stop complain about it.
mate is old and stable. It is what gnome used to be when I started using gnu/linux.
It doesn't have any cool features, but if you want something that isn't so flashy and just gets out of the way, use that.
xfce, more features than mate, but not in the same camp as KDE. Doesn't use that many resources.
I never tried it.
I don't personally like it.
It used to be the default desktop if you went to ubuntu.com
, but they are changing that to gnome in the next LTS.
If you are new, I don't recommend that you start there as it is on its way out.
But a lot of people didn't mind it, but I suspect that it is mostly people who never tried anything better.
You will also hear people that they do not use a desktop and only use a window manager.
And will always belittle people who don't care as much as they do.
What it means is they made a bit more choices on what they want to run on the computer.
It does give more control, but I wouldn't recommend it until you know what you want in a desktop and then find out which tools you think is best to achieve that.
It takes a lot more effort as you find that a lot of services is things you never cared about but need anyway.