I have several and there are pros and cons to different designs.

I have a Galco Executive for the PP series pistols. and it works well with a small pistol like the PP, PPK/S or PPK. But tie downs are not an option, and it really needs to be used with a small pistol and a fairly snug fitting cover garment like a suit jacket - which is exactly which it is designed for.

I also have both the Galco Miami Classic and a Jackass rig. The choices really come down to whether you want to carry the pistol or revolver horizontally (or something close to it) or vertically. Smaller, shorter barrel pistols and revolvers carry well horizontally. The smaller the better, especially if you are thinner built. Both can utilize a tie down and it's not hard to make a tie down for them.

I also have a Triple K holster that is very similar to the Miami, classic. All the hardware is metal which is a plus and they are a lot less expensive.

Larger pistols or longer barrel pistols or revolvers carry better in a vertical holster.

In terms of vertical holsters, I also have Bianchi X15 holsters in a couple sizes, as well as the Goodrich and Gould equivalent. The latter are a bit thinner profile in general and that's a plus as the Bianchi can be a bit thick. The plus is the harness is very comfortable and they are very secure with excellent tie down arrangements.

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While I have several, for several different handguns, they are still a limited use item. I prefer one in the winter when I wear a vest pretty much all winter without it looking out of place, but they are non starters for concealed carry in the warmer months.

Even in the winter, with a vest you need to make sure the arm holes are not too large, or the straps will potentially show, depending on how the holster is adjusted.

They work very well in a vehicle, provided the cover garment is left unzipped.