Seattle don't have to be Vegas good to have a brighter future than Buffalo. If they come out of the gate underbaked, then they are in a position to start accumulating high picks in a pair of drafts people are salivating over, and can start stockpiling them/using their cap space to create a great future team. In this scenario, they're the same rebuilding teams, a bit dependent on the luck of the lottery, and with Buffalo having some building blocks in place but with Seattle able to weaponise cap space a lot better. Which is a kinda even scenario, maybe tilted a bit Buffalo.
The big difference that makes me give it to Seattle though is so far Buffalo are run by people who are seemingly morons in this field, who hire other seemingly incompetent people, while it looks like Seattle aren't. Buffalo's future should be bright, but if they keep on handling it like they have so far, it will be anything but.