Konqueror would seem to be the best file manager for power users and programmers.
As far as I can see, file management really isn't a big deal for programmers. IDE, source control system, build automation tools, web browser, and of course a shell with the usual POSIX utility suite -- each of those things is a big deal. But Finder vs. Windows File Explorer vs. Thunar vs. Nautilus? I'd be curious if anyone can show that the choice has any measurable impact on productivity. It seems to me purely a matter of taste.
I stopped using KDE and Gnome years ago, except to try them out periodically to see where they're headed. And pretty much it's places I don't particularly care about. I won't be arrogant and say that makes them bad or stupid, it's just means they're not for me. To me the desktop wars are like college basketball; if other people are into it that's fine by me, as long as it isn't compulsory.
If there are enough people who DO want to go where these projects are heading, then KDE and Gnome will do fine. If they aren't, well, I'd feel sorry for all the people who put so much work into them. There was a time when these projects were critical to the future of software, but not anymore. Pretty much any one desktop system could disappear over night -- even (or perhaps especially) Windows. -- and it wouldn't be the end of the world. There's a healthy field of choices now, which is good for users if rough on the legacy of pioneering developers.