ExxonMobil is the largest supplier of automaker brand lubes in the U.S. (Honda, Toyota and others so they must be doing something right.) That doesn't make ExxonMobil "best", but they're certainly competitive with other blenders. Chevron Supreme (if you can find it) is now identical to its corporate stablemate, Havoline - same high moly and all. Definitely worthy of consideration.
(Off topic, but I noticed that the Rancho Cucamonga WalMart is stocked with SuperTech conventional quart bottles which no longer have "WPP" molded in raised lettering on their bottoms. It's the square encapsulated "G" instead. I'd noticed this first with 5 quart jugs of these SuperTech oils using identical jugs ("PlastiPak" jugs, though) to those which Pennzoil and Quaker State oils come in late last spring and more recently with the quart size bottles of SuperTech full synthetic (with the "G"). I'm increasingly leaning toward the idea that WalMart has switched suppliers and is using SOPUS instead of Warren Performance Products as their principle supplier - at least here on the west coast. If so, I imagine the current west coast SuperTech motor oils would most likely be relabled Formula Shell conventional and full synthetic product. Royal Dutch Shell's in a death grip with ExxonMobil worldwide, so the company's U.S. arm may be willing to offer a major retailer such as WalMart attractive discounting (and WalMart's noted for squeezing their suppliers' nickel 'till the buffalo poops) for a long-term contract. When competition heats up, consumers win.