My question would be, how many of those voting Glock have actually any experience with the SIG P-320.
I've noted that many Glock guys are not the most adventurous when it comes to experimenting with other platforms, sticking almost exclusively with Glocks. Especially the younger and/or newer shooters.
Whereas, my casual survey of my crew indicates that all of those who've gravitated toward SIGs have quite a bit of experience with Glocks.
I once was issued the Glock 23 for a duty pistol. It was okay, but did nothing for me. We then went to H&K, and from there to another polymer-framed striker-fired pistol, which even a lot of the former Glock fans decided they liked (especially the latest version).
To answer the OP, I'd echo those who say, "get what you shoot best." Frankly, I believe (and this is purely subjective, of course) that the 320 (how about the 320 Carry as an example) has better ergonomics, a much better trigger, and far better factory sights than the Glock 19 (which seems to be all the Glocksters' favorite flavor these days).
At the end of the day though, it's only what you think about the gun, who cares what others prefer?