Which will be the best breed ?

Since you have a room mate in what I'm guessing is a small setting, I'd advise you to get a medium to small sized dog. Will hair be an issue for you? If so, I'd gt a short haired breed. Boxers are the first thing that come to mind for me. And Labradors. I think these two breeds are friendly enough and suitable for your current living situation. I hope this helps.