I would definitely recommend Stefano's place, Stefano welcomed us personally and had nice welcoming touches, the apartment has everything you would need (including many Rome guides!) and very good wifi, it is on a residential street and not directly on the street so nights were calm. We slept well with the room window closed and the fan on (were there in mid-September). The area is also very nice, after having stayed in Monti it was nice to experience a less touristy neighbourhood (although major attractions are easily accessible within a 20-30 min walk or more quickly with Tram to Testaccio and Trastevere or metro Colisseo to get to other places), there are nice restaurants nearby and around Testaccio. All in all a great stay!