I have over 1500 different cards in my collection (plus about 200 doubles). I'd have to say my oldest, by printed calendar date on the card is: PSA B737 from 6-21-68. I have some others from 1970-72 such as American B747 and DC-10, Delta DC-8, TWA B747 (1/70.... first edition), TWA B707, United B747 (another first edition) and DC-10 (first edition) etc.
Rarest.... Dong Ah Construction Co. J-31 probably tops that, along with a version of Air Florida card I have. My Kazair West Mi-8 (helicopter) card probably deserves mention as rare.