My favorite edition to date is 1e.
In no particular order (and likely not a comprehensive list);
*I like its slightly clunky mechanics, its stat based limitations on things, it's To-Hit/Save system, its Save or Die stuff, its % based treasure charts by Alphabet letter, its % based magic item tables, that alignment means something, etc etc etc.
*I like it's art.
*I like the vision of the game that it presents.
*I like that character creation & advancement is fast & simple.
*I like that (with the exception of the Unearthed Arcana book) these are books that will survive decades of HARD use & even abuse. I own multiple copies of some of the 1e books for convenience. I've bought multiple copies of the 5e PHB & a 2nd MM because they can't survive normal wear & tear.
*I like reading Gygax's stuff in the DMG.
*I like that 1e always feels....unfinished. It's sooo easy to house rule.
*I like that there's very very little errata.
*I like that no two groups will actually be playing 1e the same.