As to the "Glock vs HK vs Sig" question... I can't think of a modern Glock, HK, or Sig in a personal-defense appropriate caliber / platform that I would not trust to defend my life. All three companies make very high quality, reliable, firearms. In terms of what I have chosen to purchase over time, I have more Sig than I do HK or Glock.
Every single "which is the best" argument is going to boil down to a whole bunch of variables around price, purpose, fit, feel, outfitting, etc. The very best gun for one guy will be different than the very best gun for another guy. The very best open carry duty gun will be quite different than the very best concealed carry EDC gun, which will be very different than the best range day plinking for fun with family and friends gun, which will be very different than the very best IPSC Open Division gun...