The OG hoods are quite thick in places and quite hard to give them that distinct Shimano look/shape but the Hudz are softer, have less bulk and suit my hands better.
I can't comment on the Sram or Campagnolo versions but the Shimano ones definitely make a difference.
I don't like Shimano hoods so I replace them with Hudz which are softer and have (for me) a better shape.