For blued guns, I'm a traditionalist and prefer walnut. Although, for a large framed blued guns with large grips, I really like the most white maple (curly or birdseye) finished with a non yellowing finish that I can find. For stainless guns, It depends on the guns intended use. If it's a working gun, I think rubbers are fine and infinitely practical. For a range gun or for just showing off, a really dark wood is my preference. Walnut will do in a pinch. In fact, nicely figured walnut is such a traditional grip material that it'll do on any gun, any time. I've even seen a very attractive AR with walnut furniture. For nickel finished guns (not my cup of tea) I like stag horn with just a bit of bark. Rosewood, I like the look of what is called rosewood. Realize that the real rosewood tree is nearly extinct. Other, more common red hued wood is often substituted for and called rosewood. Sometimes, even a whiter wood is stained then laminated to produce what the manufacturer calls rosewood.
Even still, I've seen G10, micarta, various laminates, even metal grips in the correct context look very good. In the wrong context, not so much. Sometimes, what may upon first glance look odd, in time may actually grow on you.
