I've found the regionals to be hit or miss. I've been on Endeavor flights where they hung my coat. I've also been on Endeavor flights where the flight attendants completely ignored all of the coats, so I folded my coat, reached up, and stowed it in the overhead bins on the A side that don't fit anything else, meanwhile, all the passengers with suit jackets simply hung them off the seatback in front of them. Same experience with Republic; either hit or miss.
I haven't been on mainline with a coat yet, so I don't have a comparison.