My favorite carving knives are stockman slipjoints and puukkos. I like the puukkos for rougher shaping or extended work. The acute Scandi grind (Make sure it has no secondary bevel) cuts very well into the wood and the handles are generally palm filling and comfortable. The stockman is nice because it offers small, thin precision blades. You get a wharncliffe, which is great for detailed point work, as well as the spey and clip point blade which make good general use whittling blades.
To me a crucial aspect of any knife I use for whittling or carving is an acute edge angle and the highest degree of sharpness I can acheive with a highly polished edge, which compliments the push cuts you'll be doing. Most knives come ground in the ballpark of 20 degrees per side. I prefer something between 6 and 10 degrees per side for a dedicated whittling blade, and again I give it a very finely honed edge followed by a series of different strops. Handle comfort is important, but the better your knife cuts, the less force you'll have to use, which means prolonged whittling won't be as tiring. The acute angles also let you hold the knife at a more comfortable angle IMO.