I went thru this same mental excercise and also put Idaho at the top. Much of it really isn’t as cold as you’d think, but cold is a minor minus from my perspective.
Add millions of residents, and it might not be so nice.
It attracts hardy people and helps keep the riff-raff out.
Eastern Washington is similar to Northern Idaho, mostly conservative, with no state income tax and few regulations. Weather is not all that bad, gun laws are not all that restrictive, all in all, a good place to live. Only drawback is high unemployment, but most folks here are like the original settlers and deal with it.
I was born and raised there. I'd love to go back but I'm not independently wealthy. I left because there were no jobs. The state still has the same problem so if anyone plans to move there they'd should either have lots of money saved up or a job in advance.
Add millions of residents, and it might not be so nice.
And there's the rub. To create jobs industry is needed. Idaho's "no lunch bucket jobs, no unions" policy has so far prevented that from happening. But it's not a paradise unless you already have money or are living on a generous pension.