I think this probably has more to do with your personality than bicycle touring. Are you comfortable spending long hours alone? Can you get enough human interaction from strangers on the road? If so, solo. If not, than find a groupie and realize the sacrifice in flexibility you must exchange for their company.

On a related note: On my long training rides and the first couple of days on tour I don't talk much to anyone; my human interaction bank is full. From day three onward small talk with shop keeps, waitresses, other cyclists, and random people on the road become enjoyable as apposed to arduous.