Back in the 1960s, most automatic transmissions were less troublesome than the 3 speed manual transmissions with the column shift. There were some exceptions–the 1955 Buick Dynaflow automatic gave a lot of trouble. Some of the Borg-Warner automatic transmissions in AMC products in the late 1960s and early 1970s were problematic and AMC switched to the Chrysler automatic transmissions. However, the GM 4 speed Hydramatic and the Chrysler Torqueflite transmissions were quite rugged in those days. The GM Hydramatic was even used in tanks during WW II. There was a company that beefed up the GM Hydramatic transmissions for drag racing–these transmissions were known as the B & W Hyrdrostick.
Back in 1970, I had the synchronizers give problems in the manual transmission of the 1965 Rambler that I owned. The transmission man that repaired the transmission advised me not to buy another manual transmission–he said that the automatics were more reliable. He said that the manual transmisisons were designed in the 1930s when the engines produced less torque.
I think that the manual transmissions in most modern cars have been improved, but if maintained with 30,000 fluid and filter changes, today’s automatic transmissions are reliable. The weak link in a manual transmission is the clutch. My advice would be to purchase the car with the type of transmission you feel most comfortable driving.