Amazon currently has 128GB Lexar cards on sale as 2000x and 1667x cards. It’s very easy to way overspend on SD cards that your camera can not fully utilize and the price of 250MB’s cards is plummeting right now so that is the sweet spot for price and performance at this time. The only reason to shoot a 2000x card in my opinion is if you fill the buffer of your Sony a9/a7R regularly or if you like to buy the fastest card you can for how they will perform in future cameras.
I currently use Lexar 1667x and 1000x cards in all of my cameras, but I have a pair of Lexar 2000x cards for when I am shooting rapidly moving subjects at 20-30fps.