Prag personally I like the wood better for a using khuk.
Wood is much more "grippy" than horn even when the horn is sanded to less than the high polish it comes with, even when the wood is more highly finished than the horn.
The only way I've ever lost control of a wood handled khuk was when the handle was just plain too damned big for me to hold onto and yet if it had of been horn I would have lost my grip on it even sooner!
As to which one is actually better, well now that's where I consider the personal choice to come in.
A good hard well seasoned piece of wood is hard to beat on any kind of knife and as far as longevity, check out all the old WW I & WW II khuks that have wood handles that are still around, still in good shape and in some places still in service.
Another good reason for wood is that it is much easier to work down if the handle is too large for you personally.
I also believe wood to be easier to care for in the long run. Barring anything except being run over by an Abrhams Tank the wood hndle will last as long as the horn, however being ran over by any thing of that magnitude would no doubt destroy any handle material unless the treads caught the khuk just right.
Personally I find the wood to be "warmer" than the horn as well which is a real plus for cold weather use.