Um, there are many more companies with their brand on oil filter cannisters than there are companies that actually MAKE filters. Purolator, Fram, Wix, Hastings & a few other assemble most of the filters found on automotive engines in the US. I suspect the number is smaller still if you look at companies that actually manufacture filter media.
If you press these companies on who actually makes their filters, they may fess up, but then they will tell you how their filter was "specially designed blah blah blah...". That means "We went to a filter assembler, asked then what our options were; then we picked one."
Amsoil doesn't manufacture filters, nor does Mobil. It's all halo-effect marketing. You'll likely get the best combination of performance & price buying from a company that makes filters.