Have you actually measured it? I’ve had production workloads in us-east-1 for over a decade and haven’t seen it be notably different than the other regions. There’ve been a handful of times where there’s been a truly regional outage (17 minutes of network connectivity in 2011) and a couple of broader service outages (S3, IAM), but it’s not like the other regions never have problems.

In general most of the time when I’ve heard people say “us-east-1 is unreliable” it’s ended up that they’re really telling you that they were in just one AZ, thought the RDS multiple AZ mode was too expensive, etc. and standard architectural guidance would have taken care of it.