As a solo traveller I would recommend Casa Ale.
The place is in a strategic location: a few minutes walking from the train and bus station, in a quite, safe and handy neighborood, not far from the city centre (about 20 mins walking).
The house is very clean and quite (but I guess that the level of "peacefulness" will also depend on the people you are sharing with during you stay).
Yamina and Francisco are a very nice couple, they don t live there but they will make sure you have everything you need and they will assist you all along the way with clear instructions (ditections,self checkin etc) and nice suggestions (what to visit, where to eat...).