I guess this needs to be broken down into aircraft and armor for me, since I own an equal quantity of both.
Starting with aircraft, the 1/72nd scale, Gemini Aces, Spitfire Mk IX, flown by Frances Gabreski, is a phenomenal piece in every way, shape, or form!!
With armor, I would give the nod to my HobbyMaster, 1/48th scale, Soviet IS-2 tank!!

This is an excellent piece!!
