Are you allowed to modify any of these guns or are you talking bone stock to bone stock?
My personal opinion having shot a lot is that G48 and P365XL are within noise of each other and it’s not a significant difference to lose any sleep over. Especially if you are okay with aftermarket Glock triggers like the Overwatch Poly DAT, they’re really close performance wise.
Stock to stock, I’d give a slight nudge to the P365XL due to trigger.
Personally, I like the factory optic ready slide on the Sig and the modularity of the FCU with regard to grips and slides.
You really can’t go wrong with either.