Although somewhat expensive, Lugers are classic. Top to bottom, DWM Dutch contract, WWI P04 Navy, Mauser G date police, Mauser BYF 42 "black widow"
I started off with an AC43 P38 (center) for a vintage semi pistol. The P38 was very innovative and holds a special place in history. Look at the Beretta 92, and then look back at the P38. Also pictured is a AC45, BYF44 (two tone), AC41 (two matching mags), and a CYQ.
How about a S&W M&P aka pre 10? They were made for many years, and offered buyers many options, which made for several different variations. Any 5 screw is over 50 years old, and many 4 screws are as well. Here are mine, all are 5 screw.
Another favorite of mine is the Colt Woodsman. First generation woodsmans and all 2nd generation woodsmans are over 50 yrs old, but only earlier 3rd gen woodsmans are. They are high quality, great plinkers, and were designed by John Browning (the pre war version was).