shoulder rigs ...
I owned a leather Aker Comfort Flex shoulder holster(left hand) for my Beretta 96D .40 pistol. I liked the shape & design. It carried the firearm at a canted angle which conceals better & speeds the release which lets the weapon
fall into your grip,
. A regular snap holds it securely.
The Aker holster straps are wide & has no elastic, buckles, snaps, hooks etc that can break or wear out quickly.
Other styles I like include the shoulder holsters from Galco,
Miami Classic II, Kirkpatrick Leather, High Noon Holsters(Skin Tite version). I prefer the holster styles that allow the off side pistol mags to be held at a horizontal angle.
I think this format conceals better & frees up the real estate around your waist/belt area. If you carry gear or a 2nd gun(back up) on your belt, the shoulder holsters magazines won't bang or interfere with the other items.
To me, vertical holsters fit better but the horizontal styles conceal better and feel better after extended periods; 10/12/16 hours.
I'd add that many gunners and cops like quality leather that breathes & will hold up for years. Natural colors or holsters without dyes or waxes that can stain clothes are good,
. The High Noon Skin-Tite is synthetic but it's made to avoid scuffs, nicks, wear. I'd see using that for open carry, low threat areas, outdoor use where you'd want a rugged shoulder holster but deep concealment isn't a big issue.