You'll universally find a much better healthcare system (e.g. health insurance not tied to your employer), with the exception of the UK. You'll find a humane immigration system that doesn't kick you out if your employer decides to screw you over (again with the exception of the UK). You'll generally have some form of state support if you lose your job instead of being thrown to homelessness. Etc etc. The US is a second world country nowadays.
And any children you might have will be far safer, and at lower risk for severe mental health problems.