Either one or two, depending on the day. If it's a one-knife day, I carry a Peanut, mini-Trapper or small Senator. If it's two-knife day, I add my slim, lightweight Vic Cadet in my back pocket next to my wallet. To me, the Vic Cadet with its Alox scales is just an (incredibly useful) tool.
The bone/stag-slabbed others are a tool, plus they are more. They feel more a part of me. Why do I feel more affinity for the natural-scaled knives? I can't really say, except that they feel more a part of me, and I like the way their aesthetics is beautiful and functional at the same time. They also bear the marks of my using them better than the SAK.