How many shots its took to take out (whatever was being shot at) at what angel, what range, what caliber, before it succumbed (sunk-fell out of the sky-burned up-fell over). What was most efficient, quickest, cost effective, sturdiest, reliable. What was (either target or weapon) easiest to operate, idiot proof, portable, concealable, affordable, sell able, and of course "looks" best. That is if someone payed all my bills for me for the rest of my life so I'd have the time.
I suggest getting a copy of Principles of Naval Engineering NavPers 10788-B. Chapters 2 and 3 will thoroughly answer your question. Now, one thing I would like to get copies of are the TO&Es for various air force's squadron support units and larger maintenance units.