Not many solar covers will last beyond a year, or two at the outside. Those that do are much thicker, much heavier, more bulky, and a PITA to put on, take off, and to store. They also cost proportionally more.
Since the difference in heating performance is minimal, (if any), best bet is to buy the thinnest, lightest, and cheapest cover you can find. When it has served its time, throw it away, and repeat.
It may seem wasteful, but I’ve tried a number of the heavyweight ones, and that’s my conclusion. The average cost per year, and the total number of pounds of plastic to dispose of over time remains similar, but handling the cover is much easier.