On my Note 3 I originally bought a SanDisk Ultra 64 GB microSDXC Class 10 UHS-1. Had nothing but problems with it randomly "ejecting", even thought it was solidly seated. Per recommendations I got here on Reddit, I purchased the Samsung Electronics 64GB Pro microSDXC Extreme Speed (UHS-1) - which has worked perfectly for 6 months now.

So, get the Samsung card and save yourself some pain.

Here are some links for the product in the above comment for different countries:

Amazon Smile Link: Samsung Electronics 64GB Pro microSDXC Extreme Speed (UHS-1)

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