The Sterling thread and my desire for one makes me think that collectables have nothing to do with being the best gun. The best collectable to me is the obscure, often short lived but ultimately interesting for some reason, maybe only to me, and quality made gun.

Examples:
Sterling
Haenel Pistols
Ruttens Browning AirStar -my battery is still charged after 3 months! Lol
Though classic, my new to me BSA Standard.
Old Crosmans