You see very, very few H&K's, Sigs, S&W autos and Rugers in competitive forums, notably USPSA and IDPA. For USPSA, it's hard to beat a correctly set-up STI or Glock. In IDPA, you don't need anything more than a 1911 or Glock in 9mm. Glocks are cheap and run for several hundred thousand rounds. 1911's have the best short reset trigger. Both 1911's and Glocks have tons of aftermarket goodies available and lots of smiths to make them run even better.
But, it's a matter of personal preference. If an H&K works for you, go for it. Personally, I don't see the advantage to a large, heavy, clunky gun with no add on goodies, wierd trigger, no one to make it run smoother, that costs alot, not including hicaps.