I’ve used a towel style bath mat for decades, I think it’s the most hygenic. It goes on the floor to shower, then gets hung to dry between showers.
I lay floors and hadn’t seen a “permanent” bath mat in years but ran into one today. It was that typical shag rug style, bright pink. This was a clean house but it was strange to me, I didn’t think anyone used those anymore.
I do have a knotty shag looking bath mat, but it gets hung over the side of the tub after each shower and thrown in the wash with towels every week. It’s just a cheap thing from ikea, but matches my (more expensive) towels
I used to have towel ones but a little cushion is better.
I primarily look for no backing . While non-slip is certainly important, I prioritize something flexible enough to hang over the edge of the tub and that can be washed frequently without falling apart. I’m not sure what athletics people get up to that need the rubber backing anyway