schneeland
Hero
Like @overgeeked, B/X D&D is roughly the level of crunch I'm comfortable with (not necessarily its idiosyncrasies). On the other hand, if we go lower in terms of crunch than, say, Whitehack or Dungeon World, I tend to find such systems not that fitting for campaign play (I do like at least a bit of mechanical underpinning for my character concepts and also some room for play stat development).