So, I finally played SM3DWorld and...

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3D World isn't the paradigm-shifting masterpiece that Mario Galaxy was, but it's still a great game.
The controls are tight, the level designs are elegant, sound and visuals are beautiful, and it's polished to a sheen only EAD games ever seem to achieve.

I'd rank the 3D games:
Galaxy > Galaxy 2 > 3D World > 64 >>>>> Sunshine