I'd have to vote for the all-steel 10-speed bikes from the '70s & '80s made for Sears, Western Auto and others.
The frames are narrow tubing, inserted through holes in corresponding tubes, backed up inside by a steel collar and spot welded.
They had one-piece cranks and drop bars that were not fully bent so the drops were at about 90° to the tops of the bars.
Derailers were typically Shimano Eagle and Eagle II, with the heavy wrap around guard on the rear one.
The steel wheels were 26 or 27" and sometimes had a moderate deviation at the weld on the rims.
Brakes were steel or aluminum Dia-Compe with suicide levers.
The annoying thing is that they worked.