Frankly, the search for the best of anything is likely to prove futile, as there is seldom an absolute best. One thing often overlooked is that any given material can be treated so that it will yield quite difficult qualities. Consider the following picture:
The top knife, a custom Talonite (r) drop point hunter with full exposed tang by Tom Mayo, has linen micarta scales. These as you can see, have been polished until they are fairly shiny, and, as you probably guessed, slippery. The Kit Carson large U-2 Dive Knife, fourth from the top, uses the same material, but it is left rough to the touch, and provides excellent grip even when slippery.
The second knife from the top is the Rob Simonich Talonite Cetan; it has Titanium scales which have been grooved and bead blasted; this provides an excellent grip. A decorated Sebenza with polished Ti scales wouldn't yield such an excellent grip.
Third from the top is a custom Ernie Emerson with canvas micarta scales; also excellent gripping qualities even when wet. Although it looks rather...plain.
At the bottom is the knife which was the inspiration for the Tom Mayo design, the Mad Dog Mako. This knife sets the standard for plain, but the composite (alleged to be somewhat akin to 'G-11') scales are undeniably superlative with respect to grip under all conditions.
Hope this helps, Walt