1957 BSA Imperial Featherweight in .30-06. It's an improved Mauser design with a nice Schnabel stock, folding leaf sights, factory muzzle brake, and other features. Right now it's wearing a vintage 3x9 Redfield "Widefield" scope with the lenses wider than they are tall. It is drop-dead gorgeous. It's only 59 years old, which makes it the youngest of my favorites.
Remington Model 8. Semiauto, long recoil, small and light carbine that looks more or less like a Winchester 95. Designed by John Moses Browning. The Model 8 was made for half a century, but in 30-odd years of gun-geekery I'd never even heard of one. And when I finally found out about them, I bought one shortly after. Among its many features, the Model 8 is a takedown design; just pop the forend off, unwind the locking bolt, and the barrel and front trunnion slide out from the receiver. Mine was made in 1914; 102 years old.
My Model 1891 Mauser. Built in a factory with steam power and gas lights, proofed by the authority of His Imperial and Royal Majesty Wilhelm II of the German Empire, machined and finished to standards that could not be justified today. When I bought it in the early 1980s there was no 7.65x53 ammunition to be had; my introduction to reloading started witb buying an RCBS form die and converting .30-06 brass. Against iron-sighted competition, the 125-year-old milsurp still scores well at the range.