Which dog would be best suited to me ?

me and my boyfriend are looking to get a dog, but which breed should we go for ?? we want something really friendly(that is the most important point), a small/ smallish dog so we can take them everywhere with us. one that doesn't need too much exercises. but would love to go a long walk. we also want one that can stay outside at night, as that is the rule for us staying in the flat. we will insulate the shed and possibly but a little heater in it. at first we thought a pug, but they cant go on large walks as they have no way of colling there Temperature down, and then we thought of a beagle. what dod you think would be best ?