I have drove in 49 out of 50 states (never been to Hawaii) and Illinois ranks the worst in my opinion. It’s like they ran out of asphalt and stopped doing any repairs 10 or 20 years ago.
To people not living in the U.S., feel free to complain about your country’s roads too.
My vote is for Belgium. Crossing the border from Germany or the Netherlands feels like entering a war zone.