So allow me to preface this by saying Mobil 1 makes excellent products. You can debate if they're above everyone else, or if they're in a class with peers, but I don't know anyone who would argue that Mobil 1 isn't a top tier product.
Similarly, Valvoline also makes excellent products. I've used their MaxLife HM oil in the past, and I'd use it again without hesitation.
That being said, M1/Mobil sells more oil than anyone else, and that makes them #1. Whether you realize it or not, the general population doesn't like bullies and as a result the person or company on top is not allowed to take shots at their lower competitors. However, we root for the little guy, and as a result we're okay with lower people/companies taking shots at those above them. You see it in advertising, you see it in comedy, you see it manifest itself just about anywhere it's applicable. You're allowed to punch up, but if the company at top starts taking unprovoked shots at those beneath them, society doesn't like it.
Valvoline isn't stupid, I'm sure that internally they had to get several layers of approval before mentioning another company in their advertising. They had to make sure that if called to do so, they can clearly defend the statements they made against M1.
But check out the Valvoline website, they really don't say anything directly attacking M1. They claim to have 40% more oil film in one test. Elsewhere on the site they claim things like they help reduce fuel economy, suitable for all model years, they meet various standards/approvals (Dexos 1, Ford specs, Chrysler Specs, etc), exceed the latest industry standards, etc.
They aren't really attacking M1, they're just saying that their new MaxLife formula (I'm assuming that they made some change) is energy conserving, SN rated, and they got various approvals (dexos 1, ford specs, etc). You don't even have to look at test data to back that up, their MaxLife synthetic is now SN rated and energy conserving, M1 is primarily SL rated and isn't stamped energy conserving (most HM aren't).
Regardless of which one you prefer, I think we'd all agree that they're both excellent HM products to choose from. I don't understand why the thread had to descend into such bickering.