I have not seen stacked birch-bark mentioned yet. When done right, it is as durable, comfortable and beautiful as any other
natural material.
From a purely structural/functional viewpoint, G10 gets my vote hands-down, every time. It just plain works, and from a knifemaker's view, it's also easy to work with... and that makes it affordable for my clients. Micarta pales in comparison, in every regard. Carbon fiber is the only currently-available handle material that comes close in raw toughness; but it falls far behind when comparing costs and color choices and availability.
Figured, stabilized wood will always be the prettiest in my opinion. But it still has certain structural problems. No matter who did the stabilizing, I have never seen a piece of stabilized burl or figured wood that could come close to G10 or carbon fiber in any durability test. Anyone who tells you different, is full of baloney.
I personally think molded materials are just plain fugly.
But! Two of my favorite production knives (and production-knife handles)
ever are the Cold Steel Master Hunter and Becker BK-16. Both have handles made of molded materials (the CS "Kraton" is softish, the Becker "Grivory" is hard), but they are both
well-designed, comfortable, durable, and they represent a lot of "bang-for-the-buck".
Let me put it this way: I make knives for a living; I can and do customize nearly everything I own, from guitars to gas pedals. That's just how I am. I have put beans in my cupboard rehandling both those knives for other people. However... I own both a CS MH and a Becker 16 and
I have not done a goldang thing to change the materials or shape of either one's handle.
The upshot is this:
We are living in a true Golden Age of knife design.
