I don’t have any experience with the newer Shimano stuff, but I have Ultegra on a couple of bikes (main roadie and TT bike) 105 on another roadie, and RX100 (I think) on my fixie. Braking performance on all 4 bikes is prety much identical, as long as the pads are in good shape.
Never saw a reason to get anything but Shimano brakes though. I switched away from Campy years ago, hated it…