I've been using a SanDisk 16gb Class 2 (slow) card in my Samsung R10. They're only 18quid from Amazon or Play and I've been recording 1080p at 25 frames per second with no problems.
Samsung do a sweet looking Class 6 (fast) SD card with a metal fascia for 35quid. I don't think there's anything that can't do.
I've always trusted SanDisk and never had any problems with any of the (numerous) cards and sticks I've used but I've never seen any studies. I know they make a lot of flashRAM for a lot of people so, even when it's got another name on the box, it probably came out of the same plant.