OTOH, would you trust the vendor to pick the best model for you? Would you trust them not to prioritize their own load-balancing concerns first?

The descriptions are near-useless and tend to flip around, as model families are not released in sync anymore, that's true, but fortunately, thanks in a big way to subscription pricing, the choice is simple: start with the best model on offer, and when you run out of quota, downgrade to the next best (or briefly switch providers).