My favorite pocket knife for whittling is Schrade 44OT. It's like a 34OT mid size stockman with a small wharncliffe carving blade as a fourth blade. These are a little hard to find and a mint condition one brings a premium. I have picked up a couple of users on the Bay for around $20 - $25 each. Lucked into a mint one once for $35. I have seen quite a few mint in box ones go for $75 and up, sometimes way up. Reprofile the blades and you will have a first class whittling knife. Schrade carbon steel is nice.
For a larger knife pocket knife that make a good whittler I like using a a congress. My favorite congress is a Queen half Congress. I like the narrower width. That Queen D2 steel will take and hold a really good edge. It takes a while to get the edge the way it needs to be but it's worth the effort.
Once I get an edge the way I like it I can maintain it by stropping for a really long time.
Greg