The SanDisk SDXC Ultra is a top-notch memory card. With data transfer rates reaching 26.6 MBps in read mode and 16.9 MBps in write mode, it's a great choice for all kinds of devices.
Best of the rest
Good SD Card
Integral UltimaPro SDXC C10 64 GB
The Integral UltimaPro SDXC Class 10 64 GB is our favourite SD card. Data transfer speeds are fast enough for the most demanding users.
Transcend SDXC 64 GB Class 10
The Transcend SDXC 64 GB Class 10 memory card ensures decent data transfer rates in both read and write modes. Although it's no spring chicken, this card is still a perfectly sound choice for all kinds of device. There are faster options out there, but they're more expensive.
SanDisk Mobile Ultra 64 GB MicroSDXC
This memory card is ideal for boosting the memory of your mobile phone. Still, it would have been nice to see a slightly faster write speed. You'll have to be patient when saving larger files.
Lexar Professional 1000x 32 GB CompactFlash Card
The Lexar Professional 1000x 32 GB memory card takes CompactFlash to a new level. With a read speed over 100 MBps, this card is very fast—even with pro SLRs.
Sony QD-S32 S-Series 32 GB XQD Card
The XQD format beats CompactFlash and SD on data transfer speeds. The Sony XQD S Series 32 GB QD-S32 is the fastest memory card we've seen yet, outstripping even the speediest CF models. The only downside is that you'll need a special card reader to use it, and the only device currently compatible with this format is the Nikon D4.