Does the RP API and/or Amsoil OE meet the manufacturer's requirements for your Tundra? If so, then use either one. It's not what we want to hear, but statistically speaking, there have been no studies that prove a different oil is "better" over a measurable distance of time.
In the past, I had emailed Ryan Stark from Blackstone and got every single UOA they had ever done for my make and model. If you throw out the clear outliers that were tested because of and engine failure (all numbers over 100ppm, say), do you know what something like 600+ tests on that one year, one model, one engine sample set showed?
All of the wear metals (which is NOT a valid interpretation of oil "performance" BTW) were within like +/- 2ppm @ 95% confidence, regardless of UOA mileage, oil brand, oil weight, driving cycle usage, etc etc etc. Now, I'm guilty of buying way overpriced, overspec'd oils as well so this is a condemnation of myself as well. But if we want to keep GOOD oils at low prices, we should try to limit our purchases to the cheapest oils that meet the specs and run those. Look at how Mobil 1 AP flopped even though it was among the "best" ingredients... nobody wants to pay $50 for a 5qt jug at Wally World when the $16 Supertech will do everything statistically the same, within the manufacturer's recommendations. I'm sure many other engine families will show similar results for that given engine family. It's a fool's game to take UOA results from say the Mazda MZR engine and make choices on which oil is "better" for a Toyota Tundra. Have fun though, it's just money, and we can't take any of this stuff with us!
Only when you've modified the engine significantly and/or the maintenance plans does it make sense to attempt to pursue "better" fluids. I know, TLR. But it's the truth.