Alternative file managers go back to DOS times with the prominent example Norton Commander (though it wasn’t the first of its kind), showing two file/directory listings side by side to better manage content of floppies, hard drives etc.
While with each new OS version the default file manager improved, the market for alternative file managers stuck around and more software popped up over time.
I have used Total Commander for quite a while in the past, but when I discovered Speed Commander, the better user experience / more modern interface won me over, combined with a reasonable price for the full version and subsequent updates.
I have switched to it at version 13 in 2011 and stuck with it ever since, usually upgrading to newer versions pretty quickly.
You can find it over at https://www.speedproject.de/ (German website) or https://www.speedproject.com/ (English website), with screenshots showcasing the different features as well as a 60-day trial version. The full version costs around 40€ (or 60€ for the Pro version with some additional integrated features like burning discs or cloud access to Dropbox, Google Drive and OneDrive). Once a new major release version comes around, an update is also possible for a reduced price of ~20€ (or 30€ for the Pro version).
Starting with version 17 the app now requires an activation, but it is pretty lenient with that, you get 5 simultaneous activations with your license as well as 5 USB drive activations. If you require even more, there are 2 “family pack” expansions that you can purchase, adding another 10 or 20 licenses depending on your needs (20€/30€ respectively, for both the regular and the Pro version).