In case the title of this post wasn't obvious, and puntastic enough, I recently finished Portal 2 and Bastion.
Here are my thoughts on both:
Portal was superior to Portal 2. The primary reasons for this being ones that can't be replicated. The twist in Portal where you escape from the final test chamber, and the newness of the experience really made the first Portal game stand out, both made it a step above Portal 2. Even so Portal 2 has great writing, introduces new mechanics to go together with the original portal mechanic, and is all-around top notch in it's delivery of all those things.
This game is probably in third place, behind Saints Row: The Third and Skyrim, for my top game of 2011. For an independent game (Despite being eventually published by Warner Brothers) that's a pretty big accomplishment. The art, music, and emotion invested in each of the moments really makes the game shine.
(Editors Note: I wrote this up briefly a few months back before being buried in college work, I figured I would put out my initial thoughts on both games after having completed them.)