My favorite has always been AD&D 2E.
I DM almost exclusively, and the worlds of TSR are my playground. 1E books were exceedingly rare here in Brazil (to the point where the only ones I actually saw during my youth were xeroxed copies), and 2E dominated the market and the gaming tables (challenged only by Vampire/Werewolf, which were wildly popular in their heyday).
5E seems to me to be a bland mix of 3E and 4E and though I liked 3E after a while, 4E is the devil. The stench of its bones is still present in some parts of 5E. I bought the core books, read them, and decided it would be best to just play anything else (my current campaigns are a TOR one with my experienced group and a Basic Fantasy one with beginners...I try to mix Call of Cthulhu in whenever possible).
It's exceedingly difficult to convince anyone to play 2E though, so my last campaign using the ruleset was a few years ago.