I’ve been running a 600x Class 10 Lexar Micro SD for the last 8 months with great success. They are now offering improved read/write speeds in the new 633x models with up to 95mb/sec.
They can be identified by the distinctive blue/black colour combination. I have a couple on their way for test.
2 x 633x cards landed today. Quick speed test confirms that they are an improvement over everything else I have used to date.