TWA 707 1979, ORD - SFO. I changed my flight from a UA DC10 just so I could fly on one before they were phased out. Have also flown the DC8, DC9, DC10 and L-1011 but haven't made the MD11. In those days the US airlines would all accept each others (paper) tickets but would put little stickers on them to change the flight details.
Not to neglect Airbus, have flown all the models except the A310. Fortunately I flew on Nancy Bird Walton last year before her current dramas. One posting on Pprune suggested Airbus may be taking VH-OQA back to use as a test machine.