I feel like its complicated... larger heavy fighters (usually) have more fuel, larger number of missiles and better avionics suite & radar which may be quite helpful in an engagement, given that one does not, and in fact cannot just throw in however many fighters one wants into a specific airspace (AKA significant numbers advantage would be relatively unlikely). But again generally speaking heavy fighters are more expensive and takes longer to maintain, so it is entirely possible that smaller fighters can better maintain a control of an airspace by being more capable to patrol and defend said airspace due to it being easier to keep in fit shape.
IMO in the end the best scenerio would be a mix of both types and let them work together to cover each other's weaknesses (which is also what many air forces seems to have been gravitating towards)
