#1: Yes, Pierce is all-you-can eat which means you can have as much as whatever you want for the same price :O It's kind of nice to be able to sit around and chat for a while with friends and be able to go back and get seconds or dessert or both lol..
#2: Pierce's dining hall is IN the dorm. This means you can roll out of bed on Saturday, fall down a few flights of stairs, and grab an omelet to start your day! This is not trivial! When it's less than 20 degrees out, chances are you're really not gonna weather the weather just for some breakfast at Bartlett.
#3: Bartlett food is better than Pierce food. It's fresher, more diverse, and just better. There's just no arguing it..
#4: What does not kill you makes you stronger. When all those Bartlett-eaters have to face real life and cook their own food, their disappointment will be so immense they probably won't be able to function for months. Piercians on the other hand will adapt extremely quickly, stomaching their odd creations with delight, happy just to know what actually is in their food
So.. 3 to 1. Obviously Pierce wins. :P
Don't stress too much about it, you'll probably be happy at either place. And it might happen that no matter which one you put 1st or 2nd, the housing people will know you're a fit for a particular one and put you there anyhow.