I've played OD&D, B/X, 1E, BECMI/Rules Cyclopedia, and 2E over the years.
When they were first out and I was a kid B/X was the starting point and everything else (BECMI, 1E, even 2E splatbooks) was generally used as an add-on to those core rules.
Post 2011 - when I started playing again I've...