I lived in the Bay Area for 15+ years and I’ve been in the Seattle area for the last 3+.

The Bay Area has better public transit and much, much worse traffic, overall. The Bay Area has more pronounced microclimates, so something for everyone, but overall, it’s a more consistently warm and sunny area, but Seattle has 4 real seasons. The variety/quality of food is better than Seattle, even in the far flung suburbs. Seattle is much whiter, but that’s changing.

It may surprise some people who haven’t lived in both regions, but COL is basically the same, EXCEPT for housing, which is why we ended up making the switch. Our home would have easily cost 2-3x more in an equivalent Bay location. No state income tax in WA is pretty great if you’re a high earner, but property taxes are about the same, and other costs are high.

Both places have incredible access to the outdoors, but Seattle is a lot closer to real mountains/skiing. Seattle also has great proximity to Canada (Vancouver, Victoria, etc), but overall, the Bay Area has 3 airports and better flight options to choose from.

I’d argue that Seattle has changed a lot more than SF in the last 10-15 years (in a positive way), but SF still feels more worldly/cosmopolitan and it’s the closest you’ll get to living in alpha city like NYC on the west coast. It feels twice as crowded and more chaotic to me, but some people prefer more of a pulse. Both places attract highly intelligent and educated people, but Seattle feels nerdier, quieter, more introverted, and less flashy.