There are many factors that affect your choice. So I think you should decide by divide in categories: overall ranking, specific field ranking (aerospace engineering), weather and communities(cold, hot, big city or suburban, girls are hot - if you like), the money they will give you ... blah blah It's a kind of ranking of those universities in your mind.
For example:
In overall ranking: MIT is the best, so you gave it 4 points, Stanford (3 points), Caltech (2) and Princeton (1) - I don't know about ranking, this is just an example
In your field: Stanford is the best, so 4 points ... blah blah (again I don't know about ranking)
Then you will have the total scores of each university and decide according to that scores.
My friend, who had to choose between Stanford, MIT, Harvard and UCB and is going to accept MIT's offer, started this and I believe it's pretty good when you have to choose among quite equal universities.
P/S: Be sure that you are honest ) If the results doesn't match your favorites, then start again and multiple the categories you like or just choose what you felt in love with.
Have fun