Fallacy of false equivalence. You can't make a claim that so and so features balance out ergo they have the same qualities, especially when that quality you are trying to discern is not founded on the premise of parts,
but the whole. 1) Drag is not purely determined by the surface areas of the feature, but also sweep, and boundary layer interaction from other parts of the airplane. 2) Overall drag is determined by 3 dimensional interaction of air over the entire plane, not just its parts. You're analyzing 2D features to determine a 3D outcome.
Longer fuselage? We can probably say so with some certainty. Larger cross section? You'd have to convince us by taking a proper scaling of the aircraft's length, find the ratio of cross section to length, and give us a precise measurement to have any claim that's reasonably accurate. Putting them together in a split image without respect for the right scaling is not convincing. Furthermore, you're going with a frontal cross section, but the cross section changes along the length of the plane. It's a poor way to back up any claim about volume and mass.
Similar=/=Same. An isosceles and equilateral triangle look similar. Will they necessarily have the same area? No.
Was the J-20 designed using a super computer? Yes it was.
Is it possible the J-20 has a design more optimized to the air dominance role?: yes it is possible
conclusion: it is more likely the J-20 is designed towards an air dominance role.
See what I just did there? You haven't backed your claim as to why your statements should logically lead to your conclusions that the F-22 fits one role while the J-20 fits another. Furthermore, you have not asserted an argument as to what properties make for an air dominance role. Finally, nothing you have said about the F-22 has indicated anything that categorically relegates the J-20 to a deferring role.
Let us start with why aircraft have ventral fins?
A) because the area of the dorsal fin is insufficient to achieve lateral stability
B) becuase ventral fins are not blanketed by the fuselage at high AoA
disadvantages of ventral fins for stealth are
they add extra reflections, thus ventral fins should be avoided
This shows two things, the J-20`s dorsal vertical have insufficient area to control laterally the aircraft thus it needs ventral fins.
Having several sets of vertical tails does increase drag, of course size and angle of swept influence drag, but they do influence stealth in a negative way.
But here the total area will be important, you can not say it has much less drag than the F-22 because the J-20 has ventral fins that add drag and impact negatively on stealth
