Subjectively judging by both the peak, durability, inherent brilliance and execution of their business models:
Standard Oil / Exxon-Mobil
Proctor & Gamble
My goal over time is to do writeups on these and explain what made them such amazing businesses. Think an investor's version of Jim Collins' books. Before I do this, however (because it's going to take me a long, long time)... does anyone have any nominations for additions to or subtractions from this list?