Hi! I have also applied to the Berkeley Development Practice program but haven't heard back yet, although I emailed and they said they would send out results by early March, hopefully before. Have you both heard back from them?
I have also applied to the Oxford program. According to several rankings of universities for development studies, Oxford is placed above Berkeley (http://www.topuniversities.com/university-rankings/university-subject-rankings/2015/development-studies#sorting=rank+region=+country=+faculty=+stars=false+search=) (and Cornell isn't shown, but maybe this is because they teach 'development sociology'), but I guess it depends on what you want out of it. If you're looking to continue studying and do a PhD in the field, Oxford would probably be the better choice because they offer a PhD in the area (and I guess the same goes for Cornell, although obviously the focus there is more on sociology - and maybe it might be better than Oxford because there are much more opportunities for funding in the US than in the UK, and a Master's in Oxford is extremely expensive), whereas the program at Berkeley seems to me to be more oriented towards actually going into the field and working in consultancy afterwards, as opposed to academia. Hope that helped somewhat...
Please let me know if you have heard back from Berkeley since I really want to know whether I've been rejected/ still have chances of being accepted!!!!