I am certainly not the only voice here. But I agree the correct knife for you, is the one that makes your chopping, slicing, and dicing chores comfortable, and controllable. IMHO, there are but two considerations that you have to consider in purchasing a good knife, the quality of the steel, and the control the knife gives you.
Without going into a three page explanation of knives, good steel is paramount, as the steel quality determines the edge harness, how difficult it is to keep a sharp edge, stain resistance, and required maintenance. The shape determines what the knife can be used for.
The santoku is used for chopping, that is, making relatively straight up and down strokes through the food you are cutting. The problem I have with this is that the edge has to be extremely sharp for the tool to do its job. If the edge isn't razor sharp, more force is required to push the knife edge through the food. This can result in accidents, or inaccurate cuts. The knife just isn't very forgiving.
The chef's knife has a curve belly that lets you slide the knife slightly forward or backward as you push down. This is a more efficient stroke and cuts through hard and firm foods much more readily. Also, a slicing motion is required to cut relatively tough skinned foods such as tomatoes, who delicate inner structure would cause most santokus to squish, rather than cut through the fruit. Breads and meats also need to be sliced, rather than chopped.
If you need to chop foods, such as raw mushrooms for duxelles, or onions, celery, etc., either knife will do the job. In other works, a chef's knife will do everything a santoku knife will do. A santoku can't do everything a chef's knife will do.
I even use my 10-inch chef's knife for a paring knife, and to remove the stems fro the top of a tomato. But then again, I'm a little extreme. My grown children use chef's knives too, but in different sizes than mine. Sprout prefers an 8 incher, but loves her ten inch knife for things like cantaloup, watermelon, winter squashes, or to slice through a large chunk of meat. P.A.G. loves her nine 8 1/2 inch chef's knife. My son, the professional cook uses a ten inch knife for most of his work, but has an arsenal of specialty knives as well. He has a very long carving knife, and a bread knife too. The other son uses an eight inch ceramic chef's knife. In fact, three of them use the ceramic chef's knives and love them.
Another reason I like my ten incher is that the blade is wide enough from edge to spine, to keep my knuckles from banging against the cutting board while I'm working.
So, as you can see, the best knife for you is the highest quality knife you can afford, and fits your needs.
Seeeeeya; Chief Longwind of the North
