Classically, us-east-1 received most of the hate given its immense size (it used to be several times larger than any other) and status as the first large aws data center. It also seemed to launch new aws features first but that may have been my imagination. If true, I'm sure always running the latest builds was not great for stability.
us-west-2 has had outages as well but it is less common, even rare. I've been pushing companies to make their initial deployments onto us-west-2 for over ten years now. I occasionally get kudos messages in my inbox :)
