Favorite of all time? The one I've been writing for months that combines the 5e flat math, 4e Heroic tone and rules concepts, 3e tactical minutia and simulation, and older edition hard metaphysics surrounding my own lore.
As for published... eh. I've played 2e, 3.5, and 4e, and, with the right (or wrong) DM each one has been pretty fun (or utterly boring). Every game is playable certainly, but I don't think I'd want to run 2e ever, and if I ever ran 3.5, I would definitely adopt a 4e school for monster preping, i.e., simplification and reflavoring, lest my head explode, and I would never want to try and run a high level game against a high-level Batman spellcaster. It would not be worth the effort.
I guess overall, my favorite edition is 4th. It gets a lot of flak, but its a surprisingly flexible system when, you know, you give it a chance, more or less until high paragon, and only really gets narrow in epic, where you basically have to throw absurd set-piece epic combats to challenge your team, all of whom are basically super-heroes.
Also: am I the only one who likes the 4e Points of Light lore? A lot of stuff has been said about 2e Realms and Planescape, but I am rather fond of PoLand. Its a great fantasy and horror setting ripe for adventure and conflict, and the Demonomicon pretty much cemented the 4e Abyss as a permanent fixture in my mind for both demonic lore and lovecraftian horror.