A car is as good as the driver...
With modern technology, most handguns come out of the factory 99.99% accurate.They only vary in terms of durability, recoil, smoothness of the edges,grip comfort,magazine capacity,safety features, SA versus DA or both.
In terms of performance, a handgun is as good as the shooter, just like a car is good as the driver. A car well maintained will perform well and last long. So does a handgun.If the shooter observes all the requirements for an excellent shot he will consistently hit the bulls eye. That is my experience.
When I was a beginner, one day I went to the range and came back loving my Sig 9mm P226R DAK, I felt I had spent more money than needed to buy my HK45 since the Sig performed excellently. The next time I went to the range, my HK45 got all the praises and I felt the Sig needed some sight adjustment.The fault was always the gun not me the shooter!
Now having spent more time at the range and getting used to the nuiances of markmanship and also getting used to both guns, I have found that they both perform similarly and I have no preference on one over the other. Which do I carry depends on my mood.Should I need one at night at home for personal defense, I may go for the HK 45 because of its larger caliber and purportedly having more stopping power over the 9mm.This should not be a hard and fast rule because a +p hollow bullet in 9mm should stop any oversized adult with a well placed shot.So, I keep that ammo should I need to use my Sig for self defense.