There actually are such studies, but how objective they are is another question.
Some of the official histories and official surveys produced by the USAAF/USAF after the war give interesting facts, but they don't break out kill ratios by exact type of aircraft shot down. Also, such stats ignore factors like missions assigned to a particular aircraft.
In short, it's not always about numbers, but often it's about something intangible . . .
Exactly. One of the truisms of air combat is that, all things being equal, a good pilot in an inferior aircraft can beat an inferior pilot in a superior plane. Also, what makes a plane "great" depends on a number of things not easily captured by a flight sim; range, serviceability, reliability, quality of radio and navigation equipment, how fatiguing the plane was to fly, etc.
Then there are the human factors, which no flight sim to date has really modeled well. It's not just gunnery and flying skill that's important, but also morale, health, fatigue, fear, alertness, teamwork, tactical doctrine, personal initiative and physical courage.
Rather than trying to capture the quality of an aircraft via kill ratios, I think it's more useful to read flight reports by test pilots who had a chance to put various aircraft through their paces. Even then, the data isn't perfect.