These two schools are quite comparable in micro theory. So you need to know what kind of research interests you more. Also it largely depends on what kinds of financial packages you receive from them. UCSD requires teaching in first year, which is a bit annoying. Concerning applied micro, I believe Columbia is better. I personally prefer Columbia because apart from its economic department, you can benefit a lot from the business school. UCSD's financial situation is always a problem and I remember they even lost some faculty to Columbia GSB several years ago. Not sure whether the California turmoil will end in the near future.