Welcome to TFL.
Both guns that you had mentioned are very good. They are somewhat different, however. I'm sure you have researched the difference but to be sure...The P226 is a double action/single action gun (unless you get a double action only one), i.e., the hammer does not have to be cocked for it to hit the firing pin when the trigger is pulled. The High Power is strictly single action, i.e., the hammer has to be in the cocked position fir it to fire. The SIG does not have a safety that the shooter manipulates. The HP hasa frame mounted safety that allows you to carry it cocked and ready to fire but with the safety on. The SIG does not have a magazine safety, the HP does. There are other minor differences but these are the main ones.
Both are generally of higher quality, IMO, than say a Ruger or (&). SIGs have been known to be above average in accuracy out of the box. The fit of the barrel to the slide of my HP, however, is increadibly tight and shoots just as well as the P226. I can't really say that one is more accurate than the other as I'm only an average shooter.
One problem that many people encounter with the HP is the legendary Browning hammer bite. That is, when the slide travels back and cocks the hammer, some people like to hold the HP high on the grip and the web of skin between the thumb and forefinger gets pinched between the hammer and frame. I've had this happen to me early on when I got my HP but for some reason, it is no longer a problem. it could be that I'm unconciously holding grip lower, although I don't feel I've changed my grip any, or my hand ,as well as the rest of me has gotten fatter and the web of my hand does fold into the space betwen the hammer and frame as much. The 'fatter' part of the second theory I can confirm I am doing conciously to my dismay.