One major factor beyond performance stats, is the ability to keep them flying. Wars are not won by the best airplane, tank, or rifle, but through logistics. Having equipment that is robust, simple to maintain, in large quantity, operator friendly, with well trained crews, pays greater dividends than individual performance characteristics. Great example, the Tiger and Panther tanks. Compared to allied tanks, T-34 and M4 Sherman for example, they were regarded as the better vehicles. But when looked at through the logistics lens, they failed miserably. Harder to produce, highly technical and complex, difficult to maintain (without adequate spare parts), not in great enough quantity, and a host of other factors, reduced their combat effectiveness.
But Tiger Panzer is a cool machine and logistics is a subject so boring.
My favourite one:
I don't know what the hell this 'logistics' is that Marshall is always talking about, but I want some of it.
(E.J.King)