I love Beretta pistols, however I own both the Italian produced 92FS, and the Sig P226, both are IMO on the very short list of the very best combat sidearms currently available in any caliber.
Ergonomically these pistols are quite competitive with one another, it will of course come down to the size of the individual hand as to which seats itself the best in that hand, regardless, both are chunky in the grip, the big hit on the M9 is the slide mounted safety-decocker, the Sig's is frame mounted.
I believe the Beretta barrel to be superior to that of the Sig, and I also feel the Beretta is a bit more accurate, in fact I have other 9mm pistols that also outshoot the Sig. The Sig has a better trigger then the 92 in both DA & SA, and also comes equipped with better factory sights and superior magazines(Mec-Gar).
I've never seen the data that supports the contention that the P226 ever matched the reliability of the M9 in service trials, I'm not saying it hasn't, or can't, just that it's a very tall order to match the performance of the open top slide of the Beretta, keep in mind that the SEAL teams were firing many thousands of rounds through their M9 pistols per week before they encountered the infamous slide failures(3 in total correct me if I'm wrong).
The M9 has 69 parts, the Sig 55! If Uncle Sam ordered me to carry one or the other as a duty weapon, I would not be whining about it.....