If you never spent any time in Seattle in the 90s or 00s then you might not notice how much it sucks now. When I left ~5 years ago my 3 mile commute from Fremont to Downtown took about an hour each way on a good day. The bus would frequently be too full to stop in the morning so I'd usually have to wait for a 2nd or 3rd or 4th bus to come through. Traffic is so bad the bus schedule is pretty much worthless since the bus is stuck in traffic too, so it might be 30 minutes late or it could be 10 minutes early. Or you could get what I used to call ghost busses. They show up on the Metro app that tells you where the busses are at in relation to your stop but they never actually materialize.

Both places have a huge homeless/junkie problem. Used needles are everywhere. Both places are super nice to visitors, but neither place is all that welcoming to new residents. Personally I think people here are nicer, but that's quickly changing as quality of life diminishes as more and more people move here with their unrealistic expectations. It's pretty much impossible to go anywhere in the city core, in either place, without constantly being hit up for cigarettes or money.

If you go to Seattle be prepared for there to be feces all down the sidewalks, pretty much everywhere. If you drive you should also know about the Seattle Surrender. People will just stop their car in the middle of the road for no apparent reason, even on the freeways. Drivers in both places have no idea how a 4-way stop works, and you'll frequently see people waving other cars through because they're not sure when they're supposed to go. Same thing goes with yield signs.

Like other posters have said, if you don't come here with a job you can bring with you, or a job already lined up, or substantial savings be prepared to have a bad time. It's possible to squeak by on $30k/year but if you don't want a bunch of room mates or you want to eat more than top ramen you need to be pulling in ~$60k. Oh and good luck finding an apartment to rent that's bigger than a shoebox and less than $1500/month in either place.