I’d pick Feinberg any day of the week from the pros you listed. As good as WashU is, it’s not that much if at all better than NW and having a support system (your brother) in a city like Chicago is too much to turn down unless they blow you away financially. Also you’ll have to live there 4 years so picking a place where you’d be happy seems rather important.
Always go where you think you'd be happier. If you don't like where you are, you will not do as well--it's better to be happy and excel at a program you like, than to be uncomfortable at a program that is slightly higher ranked. No matter where you go, you will graduate with an MD. Med school is hard enough; don't add to the difficulty by choosing a program that doesn't "feel right".