Another vote for considerably less complexity than 3e. It was something of a lightbulb moment for me that if you have a thief class in the game, you don't need a ninja class or a scout class or even (really) a bard class. So 3e, 2e, 1e... all of them out the window, and it's Classic D&D for me. It's got the baseline five (fighters, mages, clerics, thieves, and monks), and that's all you need.