Which specs you care most? Design/Compatibility/easy to install/or anything else? Checked on OYSIN. It only fits flat top handguns and cannot fit EVERY Sigs or 1911s.
Yes, you are right - OYSIN won't work with 1911 style slide, so I won't use it. Looks it's made for Glocks.
What is most important for me? Magnet strength. If I use the magnet my gun eventually will be magnetized, so I'm gonna choose magnet with max pulling force 30 - 35 lb.
Design - flat rectangle with screws or 3M tape. This way I can use it for my CZ and RIA1911 in any space.