Its a tough call for me.
3e d20 with the OGL allowed tons of content and tons of options that are really cool. Downsides of balance issues, LFQW, trap options, and complex DM mechanics.
4e has balance, non/low magical options that work if you want a sword and sorcery or no real loot game, rangers and rogues that work great as strikers, great monster mechanics, evocative planar setup, and a cool mythology. Downsides of no srd, the fiasco of the D&D tools, the deprecation of the paid offline tools that worked, and lots of people hate it. My favored edition for playing with my son when he was younger.
Basic and AD&D were good and I played them from the 80s through the 90s but mechanically I prefer the later systems more.