Are you familiar with the Evutec Selenium? That’s what I’m currently using and I think it’s fantastic. It has grooves around the perimeter of the case to enhance grip there and the back is nicely textured. Soft, but not slippery and highly resistant to prints and scratches. I have the Smoke Silver version.
I hope the link I post works. As an FYI - they do not yet make (not sure if they will - Evutec seems impossible to get a hold of) an iPhone 8/Plus specific version but I have the 7 Plus version on my 8 Plus and it’s perfectly fine.
https://www.evutec.com/selenium-iphone7-case
How tightly does it fit? I tried an evutec before and it was pretty loose around the edges.