I have a 30-year-old Safariland shoulder holster that holds a 6-inch revolver vertically. I've worn it quite a bit but never worn it out. It cost me a pretty penny back in 1979 but it's been worth every penny.
I don't believe that Safariland makes it anymore.
For my Browning Hi-Power, I use a recently purchased X-15 shoulder holster made by Bianchi. It carries the Browning horizontally, which I don't like as much.
I don't much care for belt holsters because they require a great deal of effort to get the gun out if you're sitting down, as in your car or in a restaurant.
I know ... I know ... you shouldn't be shooting from your car or in a restaurant, but I work on the premise of Never say Never.
I was in a crowded restaurant in 1980 when a robber walked in, waved a Ruger .44 Magnum around, and loudly told everyone to freeze, that all he wanted was the money.
I had a Ruger Security 6 .357 Magnum in my Safariland shoulder holster -- and I did what the man said (so did everyone else).
He got the money and fled back out the door.
It would have been foolish of me to engage in a gun battle with him in a crowded restaurant, especially since his was out and cocked, and mine required at least two seconds to get operational.
Discretion is the better part of valor.
This time of year, when a coat or jacket hides it well, I prefer a shoulder holster.
If you're a fat ol' cat like me, you'll also like a shoulder holster because the darned gun isn't pressing itself into the tender skin around your waist.
I never found waistband carry comfortable.
Ankle holsters are hard to get to in a hurry if you're fat or hindered by older age.
A well-made shoulder holster is comfortable, easily accessed and secure.
Just a few weeks ago, a guy here in Utah went into a toilet stall and dropped his pants. His .40-caliber pistol fell from his waistband, hit the floor and discharged a round right into the porcelain potty!
A shoulder holster is still secure, even with your pants around your ankles.
There are a bunch of cheap shoulder holsters out there that are inexpensive and uncomfortable. Buy quality. It will last all your life and you won't regret the extra money spent.