My N=1 experience…
I have Ultegra Di2 on my road bike, and SRAM Force AXS shifters/Eagle derailleur on my gravel bike. Ultegra Di2 is very smooth and quiet, while my SRAM set up shifts with a bit more of a “clunk”. Both work beautifully I just think the Shimano is a bit more “refined”…part could be the bigger gaps in the Eagle cassette (X01 cassette and X01 chain though).