I would favor a Glock over Sig, (except for the P365 vs Glock 43, though the Glock 43x Shield Arms 15 rd mags are intriguing).
The only downside with Glock is factory sites are plastic so you may as well add at least $100 To the price tag. Sogs come in around the same price with the bells and whistles.
That being said, I will never own a P320. I have picked one up, and it felt amazing, but I’m one of those people who totally lost interest when the drop failures where happening. I know they fixed it, but their fixing it was not adequate to me. I’d take the reliability of the Glock.
BUT the P365 has been out for a couple years now with a great track record. I wouldn’t hesitate to carry one of those.
That being said, I’m pretty much sold on M&P.