I (meat-eater) am done with leather alternatives for now. A while back, I bought the official leather-alternative case for my everyday-carry Roav sunglasses, but it didn't last me very long. Frustrated with that, I ordered a custom made case with real leather, that cost me double the price, but it has been aging really nicely.
For me, paying extra for good leather, that will last longer and is byproduct of meat I already eat, seems to be the best decision in terms of sustainability. Hopefully technology will improve so that we have more options in the future.