Gyuto (Chef Knife)
The Gyuto, or Japanese chef knife, is widely considered to be the most versatile kitchen knife for both professional chefs & home cooks alike.
With a variety of sizes and shapes available, generally the Gyuto is similar to western style chef knives in shape, however thinner, lighter, made of harder steel and retains a sharper edge. They consist of a flat mid-heel section for chopping, a curve towards the tip for rock cutting and a pointed tip for precision work.
If you are going to purchase just 1 good knife, the Gyuto (or perhaps the similar Santoku) would absolutely be the knife to choose.