"I have German residency and I'm looking to convert my ATP and go to Europe."
jsfboat,
You're fortunate to have an option most of your American compatriots lack: the legal ability to live/work in more than one country.
The US Part 121 supplementals have never been the career equal of the legacy pax & freight carriers you mention. That's NOT to disparage those who fly supplemental work. It's a tough way to earn a living. I know because I began my career that way.
Just to educate those who wonder, but don't know, about how the EU option would be better than your prospects here, can you explain how a person would be better off moving back there as you're planning to do ?