I don't quite understand the poll. I've never changed the bars on a bike.
However, I have changed from a flat bar bike to a drop bar bike.
Now that I've found that drop bars are far and away more comfortable for me to ride--even with my arthritic back--I'm replacing the flat bar bike with another drop bar one for the winter. It was certainly a challenge trying to find road style frame and drop bars in something that has disc brakes and would accommodate my studded snow tires.