Anybody that suggests that a Sig 229 or 226 isn't more accurate then a Ruger SR, or a S&W M&P, Or Beretta PX4, in my opinion should re-evaluate their statement, I don't care what distance you're shooting at or what level of shooter you are, you will see a difference.
Reliability can be argued all day, Sigs are among the best, and I don't think that can be disputed. Are they the MOST reliable? Of the guns you mentioned, YES, I think they are.
And of every gun you mentioned an interest in, the Sigs and probably the Beretta 92 are more accurate than the others.