When typing, do you prefer one or two spaces after a period?
Two spaces after end of sentence punctuation. It makes reading the typed copy easier to do.
I’ve used two spaces since 1967, it’s a hard habit to break.
Why would you want to break it?
Because 1 space makes more sense with current fonts. However, it doesn’t really matter very much.
One with a proportional typeface. Two with a monospace typeface. Two spaces is a holdover from the typewriter days.