David Bowie

The Glam period alternated excellent things with others that were definitely inferior (never below sufficiency, anyway), then some brave experiments like "Young Americans," which were good even if not entirely successful. The peak was with the enormous Berlin Trilogy alongside Eno (and in Heroes there's even Bob Fripp, and excuse me if that’s not enough), where experimentation and artistic maturity came together; in Berlin, Bowie produced some of his best work. Then there were many lows and still a few beautiful highs. Great, in any case.