You've already gotten some good repies on the materials themselves, so I'd like to chime in with some other thoughts. I won't make a blanket statement or single out any given design, but I have noticed trends about how the makers *use* these synthetic materials. Generally speaking, I've noticed that many knives with G-10 and especially carbon fiber, have handles that are very flat, often with sharp corners. Even my Benchmade Ares handles are somewhat contoured and comfortable for light cutting, but if I whittle wood or do some heavy cutting, the edges of the handle really eat into my hands, even when I had tough farmer's hands. (one of these days when i get around to it, I'm gonna round them off, and regrind that blade.) With micarta, though, more often the makers will shape the handle with comfortable contours and palm swells. Maybe it's because they want to expose that pretty "grain", or because the available stock sizes are thicker?
I've also noticed that many makers who choose to work with these materials often let the tang exposed beyond the scales all around. And, often rather than fitting a proper guard, you will see knives where the blade/tang extends to form a rudimentary guard. (not saying all makers do this of course, just that it's rare to see a knife constucted in this manner sporting an ivory or stag handle) I hate this idea. I used to think it was fine as long as the edges of the steel were chamfered a little, until I used such a knife for an adrenalized thrust, and the "guard" ripped the skin right off my fingers. I still have the scars to prove it.
So, just don't get so concerned about carbon fiber vs. micarta or whatever that you forget to see if the handle is shaped in a comfortable design.