I would actually vote Directory Opus, but no lifetime license with this
price is a no-go for me.
So currently I basically use two file managers:
1) CubicExplorer, still in first steps of development but already fast and stable with a bunch of useful extra features. And it is free.
2) xplorer², the fastest FM on the "market". Using your regedit skills, you can also assign My Computer to it, although the developer doesn't really support this ...
is very feature-rich (and free), too, but the major con is that it is developed in C#, so it's sluggish and hogs resources. A pity, really...