Sopus/Pennzoil/Quaker State are my last choice oils simply because of their marketing of the Slick-50 products. Snake oils like Slick-50 are designed to extract money from the pockets of ill-informed customers, and any company which deals in them is worthy of derision in my book. I am surprised how many people hold a grudge against Castrol for it's roll in getting group III oils legally defined as synthetics while at the same time giving Pennzoil/Sopus a free ride on the much worse Slick-50 scam.
All a matter of personal opinion of course, but you asked why so little "Love" for Pennzoil. Sopus is also big time into dubious claims for all kinds of "special" oils. "Torque Power", "4x4 Oil", & "Advanced Engine" all come to mind. The modern history of the Quaker State product line is all about silly names and nonsense marketing. No surprise that Quaker State bought Slick-50 before Sopus bought Quaker State.
By contrast, Chevron-Texaco gets my admiration for making first rate products, spending very little on dubious promotions and selling the product at a good price. The product line is straightforward and the few special purpose variations (i.e. high mileage) have some decent science behind them. At $.59/quart from Kragen sales, Chevron Supreme is the bargain oil of modern times. You can pay almost $3/quart for Pennzoil at an auto parts store and have nothing extra for your money than a lot of advertising.