I've used whatever basic cards were cheap or I had around, but last time out with the XT30 doing car tracking and burst shooting, I would get hangups for 5 or 10s while the buffer dumped and the cards tried to keep up. Even switched from my Samsung Evo whatever to my Sandisk whatever. Didn't matter.
Black friday/boxing day came around and I got a Lexar Professional 128GB 150MB/s SDHC UHS-II card. I finally got it shipped and upon using it, I can burst shoot and while it's writing, go back to burst shooting. No more hangups.
I know it doesn't use UHS-II but being on the fast end, it's not a bottleneck and if I get a new camera at any point, I'll already have a UHS-II card, so win win.