G-10, I have to laugh everytime I see that G-10 gets slick when wet. I work with this stuff at least 2/3rds of a year. Paper, Linen, Canvas Micarta & G-10, G-11. Hands wet from sweat or rain, methanol, electra clean, carburetor cleaner, grease or whatever G-10 won't fail or absorb. As far as being slick when wet, I have held on to it for long periods and to me it begins to have a warming and tacky sensation. I use Micarta as well and like it. I really can't say which is better cause it's a personal thing YOU are just going to have to find out for your self. I have learned to prefer G-10 for a hunting knife cause blood and animal fat doesn't soak into it. You can get an odor that will soak into micarta for a little while. You just have to wash it (micarta) real good when you get home. Of coarse you have to wash G-10 as well, DUH! One thing I do like about micarta is that if your working out in the sun, it doesn't seem to get as warm as G-10 will and that is because it dosen't have the glass mix in the Epoxy Resin oh and notice G-10 is EPOXY Resin while micarta is a PHENOLIC Resin.
As far as natural hand materials, well if you live where it doesn't freeze maybe so. In the north country where freezing is going to be included in daily living often times, Micarta or G-10 and then you will still need gloves! Seen to many broke knife handles and gun stocks that were made from natural materials. Even if I left Alaska and went back south I will use Micarta and G-10 from now on.