Personally, I don’t know much about Brown (I only have a close friend who just got accepted). I was accepted to both Berkeley and UChicago, but…
I can’t recommend one over the other, since what you want to major in is ultimately up to you. What I personally believe is that for the two majors you mentioned (CompSci and Econ), Berkeley and UChicago will be better, respectively, than Brown. Berkeley’s CompSci program is tied with Stanford (second only to MIT), and UChicago is arguably the best (though UPenn is great too). I wouldn’t recommend Brown over either of those two for your majors.
If, reading what you said, assuming econ major, UChicago is definitely preferable over Berkeley (UChicago’s econ program is, iirc, rank #1, or maybe tied w’ UPenn), but since you’re L&S CS -aka undeclared- at Berkeley, if you wanted to do BOTH CS and Econ, then Berkeley is by far the winner. (HAAS is still pretty good).
Just because your school hasn’t sent anyone to an Ivy doesn’t mean you should go. Do what’s best for you ^^.
tl;dr; Brown isn’t the best for CompSci or Econ. UChicago > Berk for Econ only, but Berk > UChi if you wanted to dual major in Econ and CS. And you can’t go wrong with either ^^. You’ll have a good future no matter where you go.