I’m a big fan of Peak Design’s Capture Pro Clips after I figured out how to get them to work for me.
The way they are promoted for attaching to backpack shoulder straps doesn’t work for me (horizontally across the strap). It digs into my chest and arm. Using it with a Proplate also digs into my chest and arm.
What ended up working for me is using the strap’s padding to distribute the camera’s weight.
On a Vanguard Adaptor, there is a loop in the shoulder strap presumably for something like a water bladder tube, but it works perfectly for clamping the Capture Pro and keeping it from sliding down. However, the camera would eventually tear out the loop, so to add strength, I wrapped a short nylon strap around the backpack shoulder strap and then clamped the Capture Pro around the strap.
The Capture Pro also works on the strap of my Lowepro Flipside Sport. It doesn’t have a strong loop to clamp through to keep the clip from sliding down, but it does have a higher plastic loop that I like to hang the Capture Pro like a picture frame.
I also like to use the Capture Pro on my belt, but I prefer it on a Propad (clamped only to the front flap) so I can slide it on and off quickly.