Both have excellent grip if I had to pick the best I’d go with sheath but both are great .and sorry don’t really have a way to weigh them. buttons are definitely better on the onyx.I’ve use the sheath on my last 4 iPhones but for the price of the onyx I believe it will be my go to case although I have 2 sheaths already for this phone
I hope I did this right, lol. I bought this Case-mate twinkle ombré confetti for my gold 12 pro that is not expected to ship until 11/18/20 😞 Their cases are cute but makes the phone heavy IMO, but once I get my phone I’ll look for other cases.