It really depends on your preferences. Choosing the right knife, material (hardness and type of steel), type of blade and its length is very important depending on what tasks and for what purpose you want to use it.
Best to post a topic here 
If you want to buy a knife for home use this 18-21cm Gyuto or 16.5cm Santoku should be perfect for you. What kind of steel? If you use it often and are a bit more advanced user - carbon steel will not scare you, otherwise stainless steel (especially Japanese) will be perfect.
A good choice will also be a good petty and usuba knife (if you want to test yourself in carbon steel).
If you are into sushi, your first choice should be a suitable Yanagiba knife.