I also use multiple knives. My favorite carving/whittling knife to date was some sort of small, folding Gerber knife. Had a short (2.25") blade and was very comfortable in the hand. Unfortunately I lost it while canoeing...
Now I either use one of a couple utility knives or an older Mora knife (from before they became Morakniv). Like Eastman03, I'm not set on anything, and will hopefully try some new stuff soon. I guess it gets down to whatever is most comfortable, available, and practical.