as a long time user of linux, i began with kde 2 back in 1998 iirc
kde is the most complete desktop environment when you come from a windows background like me
you will not feel lost using it, it has that old windows spirit but is alot more modern than current win 11, it feels fresh and alot faster for sure
cinnamon is quite decent, i used it daily for a couple months not long ago, it is fine, but i felt it is not enough
xfce is ideal for the worst machine you have, 2 cores and 4 gbs of ram from 2006 lol, xfce will feel like a rocket, it will do the job just fine, but i end up always on kde again
kde right now is far superior to anything one can find, people keep talking about gnome, but, gnome has always had a philosophy of be like mac but better, and i dont like mac, so
lxde used to be popular, but xfce is more popular right now, there are so many desktop environments now, but some projects are long abandoned or too new, alot of them are based on gnome and gtk tools so it gnome is really important, but, it is not for me
the idea of put the iso in a usb flash drive and give it a go via live usb, is great, but i end up on kde always, fo my opinion is kde first, then cinnamon and lxde
i cant tell you that any of the popular desktops are perfect, but i am very happy in kde, you will feel growing pains on any desktop you choose, because all of them are always growing, it never stops(well the ones that are in active development and maintained)
knowing that the growing pains are always there, it is very important to choose a stable distro that does testing and doesnt push every update and hopes for the best, because some updates are problematic and sometimes skipped, other times are replaced quite fast, kde 6.7.4 for example didnt last here 3 weeks iirc, kde 6.8 is not far, perhaps a couple months away, it all keeps evolving and often big features are added
when talking about features, when i used cinnamon and xfce i felt like nothing had changed that much over the years, on kde, alot changes, often, last year i used a old version of kde on mint and i felt like i traveled back in time
you never stop the learning curve and that is a good thing, every day learn something is a good thing, in my opinion, at least