The best one is again Total Commander 5.51 after I've at last downloaded & installed & reviewed Directory Opus 6.2.0.2. If you are on Win9x, Dir Opus takes %10 percent each of Windows GDI & System resources and that at the end makes you to run only 3-4 programs at a time. That's not well for a file manager. The ratios in Total Commander are %5 to %2-3 which is approx. half of Dir Opus.
The advantage of using Dir Opus against Total Commander is only being much more customizable.
That's all.