I love the "not so perfect" and purpose built but rather cosy and makeshift hostels that make ones stay like visiting friends. in this category my favourite places ever have been:
Amaroo Park, Philipps island, Australia
Gecko lodge, Darwin, Australia
Backpackers Salta, Argentina
Travellers Rest House Sandakan, Borneo, Malaysia
the lighthouse, Kapas island, Malaysia
Nkhata Bay Backpackers, Malawi
Guesthouse Hannover, Germany, which I just discovered 3 days ago.