Bought the natural rubber one and have been using it for well over a year. It was pretty pricey but I’ve been satisfied with it. It doesn’t give off any icky chemical odors, the color is pretty, it has good suction and comes off easily, and has not molded (I just pop it off, shake off water, and hang it over the edge of the tub to dry) or stained our tub. The size is sufficient for our tub although if they had offered this color in the big size, I would have gotten that one instead.
Update:
It eventually molds despite taking very good care of it. Mold also does not clean off. In looking at other people’s reviews, may just need to expect to toss this out every year or so when it molds. Unsure about rebuying as it is pricey.