5 major priorities of a good top view

Tsutsu (joint between tail and body)
The backbone of the peduncle should be thick.

Ozara (underside of the tail pan)
The disc or the tail seat should be as wide as possible.

Oyabone (tail shoulder)
The fish should have an elastic thrust forward shoulder tail that is closed while swimming and opened when stationary.

Se (back) + Koshi (waist) = Koshiore (waist curvature)
The back curve should have a smooth bending that is not too shallow and not too deep. A good back curve gives a nice tail tuck in the abdomen.

Funtan (forward projecting head growth, cheeks)
Good buffalo cheeks provide a nice top and side view.