When I first joined the site many years ago I was a die hard Mobil-1 user. I simply believed the hype, believed the advertising, the commercials, etc, but after lurking/posting for a while I began to see a trend of higher than average wear metal counts in Mobil UOAs.
I watched, read other's comments about it, read some more then decided, for the price I was paying for it (expensive!) I would go with a cheaper, but another well known oil in Pennzoil. The Pennzoil UOAS consistently received much better UOAs than what Mobil did, UOA after UOA, which still seems to be the case today.
Some will disagree with this as well, but after adding the Pennzoil to my vehicle (truck) it ran quieter, which I happened to think was a bonus and a bonus which may explain why higher wear metals were being found in Mobil UOAs. More friction=more noise.
Mobil is the recommended oil choice for Corvette and Pennzoil is the recommended oil for Ferrari. Not sure if that means anything to anyone, but knowing the RPMS those Ferrari engines spin at, I would assume it is a pretty stout oil.
Not looking to get anyones panties in a bunch. These are my observations and my decision to run Pennzoil was based on those and what others were saying at the time, nothing more.