Yeah, 3D World was amazing, Nintendo really brought their A-game with that one. It was an absolute joy to play, just like Galaxy 1 & 2. Hell, I might even prefer it.
So many lump Galaxy with 64 as being more of a big, open, exploration-style Mario game, but hub world aside, the levels in Mario Galaxy are rather linear, and I realized this as I played it. Sure, there were some big levels, or planets. But so many were just tiny planet-->launch star-->tiny planet-->launch star-->tiny planet-->launch star-->end. The linear 3D World levels have more interesting traversal than the on-rails launch stars.