Different guns are more popular in different areas for different reasons. Im would think Sigs are more popular in Exeter, NH. If you follow the Feinstein way of thinking everyone in the hood owns a Glock. I used to live in a city where the local PD carried the Sig P226 and at a few guns shows I worked I heard people constantly talking about how they want this gun because this PD carried them. I lived in another an area where the range north of me 15 miles had mainly 1911 shooters (local PD carried 1911) and 10 miles south of me mainly had Glock shooters.
Now I do get that Sigs have turned some people off with their QC issues, some of their "exotic" designs and the version 1 of the P250 and pricing. Just look or search the Sig forum, they complain about these issues and more. I happen to love Sigs especially the P228 and a few others.
And as one guy mentioned earlier even Sigs fans carry Glocks, is true I would add M&P to that. When I managed a shop/range people came in with their Sig X5, 229, 1911 but their CCW or HD gun was a Glock of M&P, not everyone but a lot. I would be interested to see how the P224 does in becoming a primary carry option vs the other carry options.