Ideal? Hmmm, I have gave up with looking for ideal stuff (knife, car, gun, wife, etc.
) 20 or more years ago... No ideals in this world (just my opinion).
Favorite? Depending on the knife intentional use, as usually at least.
For heavy duty folders (sometimes also called as tactical) I would like G-10 for these reasons:
* it has very impressive strength to weight ratio (especially if it is dense fine fiber composite like on SPYDERCOS);
* it provides non-slippery grip in different conditions (if suitably finished of course);
* it is thermally neutral - not hot and not cold;
* it's visual appearance isn't affected too much when scratched and is relatively easy to restore the surface if needed.
My favorite heavy duty folders with G-10 handles are SPYDERCO Starmate closely followed with Military and BENCHMADE AFCK closely followed with model 710 Axis Lock.
For medium sized daily carry folders I like also G-10 for the same reasons. My favorite here is KERSHAW Avalanche.
For lightweight folders, in another words - if minimal weight and reasonable strength combination is required glass reinforced nylon is unbeatable. My favorite here is SPYDERCO Calypso Jr. Ltw. closely followed with Delica.
For gentleman's folders bead blasted titanium is very nice, has enough durable finish and provides grip sure enough for this category's knives. KERSHAW Ti-Hawk and CRKT S-2 are illustrating this nicely. Bead blasted and anodized aluminum provides very pleasant "warm" touch and visual appeal (BENCHMADE model 940 Osborne), sometimes can be quite sensible to scratching.