What is the best way to connect wires at a receptacle?
By pigtailing, if you do a good job of it. Second choice: wires wrapped clockwise under side-screws. Third choice: use a receptacle whose side-screws clamp the wires tight in holes. Last choice (and only for 14 gauge wire): the “quick wire” push-in holes on the back of the receptacle; this actually does OK most of the time and is the most common.