Let's for the moment set aside that Trump is an epic and historic screw up, because republicans agree on and stipulate to that.
The republicans would still never pass ACA repeal, never pass tax reform, and never pass a budget - their three biggest agenda objectives. Their inability to get anything done has little to do with Trump and nothing to do with democrats. The republicans hate and disagree with each other. They can't agree on their own goals or even what conservatism means.
No matter which GOP candidate you choose from the remaining 16, you wind up in the same place...
...in the middle of nowhere with nothing.