Modern and Vintage.
What sounded louder was the Polaris 1968, I mean, the Vintage E 859.
Very close in volume, but in a higher tone, the Polaris II E 870.
In the modern production, and among the watches you quoted, I'd say the Amvox I, especially in titanium, being R or not.
I guess it is due to the metal, but also to the caliber ( 918 ) , which is maybe less nicely sounding ( less cristalline ), but louder, compared to the Cal 956 ( NSA and TTP 65 / 68 ).
Nothing to see with the Water Resistance, but something to see with the Caliber, and with the metal used for the case.
Best,
Nicolas