I have Ultegra Di2 on one bike and Rival AXS on another.

Overall I prefer the ergonomics and functionality of the SRAM setup as well as the wirelessfullness (yes that's a word. look it up). Performance and reliability are a tie.

But if something happened that forced me to write off SRAM for life, e.g. a SRAM employee kicked my dog, I wouldn't lose any sleep going back to Shimano.