7.5" Chefs Knife, #22, Kiwi

I'd recommend buying a cheap nikiri (like a Kiwi or some Chinese thing)first to see if you like the format and end up using it. I bought a Watanabe and used it for a bit, but just never felt that it offered anything more than my beloved gyutos. Santokus are similar in that they are good for smaller spaces or smaller hands, but if you have a gyuto that works for you, the santoku is probably just an inferior tool for the same function. On the other hand, I use my 150mm petty all the time. You might be the opposite; I'm just recommending some testing first.