If I were to avoid a state just because of the roads conditions, I would have to avoid half the country.
It's pretty bad. I think Michigan roads are the worst, because the roads I mostly drive on in Michigan are really bad. But overall, Michigan isn't nearly as bad as you'd think. It's just that where they are bad, they're really, really bad.
Attached is a PDF file of all of the states, sorted from best to worst, insofar as the percentage of the roads in that state which are in Poor/Mediocre Condition, according to the US Department of Transportation, which gets most of the data from the American Society of Civil Engineers (which is probably most famous for getting into a very corrupt bed with the Army Corps of Engineers to create the Katrina report that virtually absolved the USACE of any and all wrongdoing in New Orleans, and got their butt kicked by Congress for doing so). The percentages are probably relatively accurate overall, but the very low percentages are likely to be a little on the too low side, and very high percentages are likely to be on the too high side, because the report uses a small source of data for each state and then extrapolates that data to the entire state roadway system. That can miss roads badly in need of repair (the very low percentage states), and can overstate the amount of need for road repairs especially when new roadway construction and maintenance gets conflated into what appears to be greater need (the very high percentage states).
The unsorted (well, sorted alphabetically by state) can be found here:
Road and Bridge Data by State
