I'm trying to make BeagleBone Black into a programmable keyboard (and mouse, hopefully).  It has one "USB device" port (mini-USB) and one more common "USB host" port (USB-A).  It boots off microSD or eMMC.  One frustration is slow speed of my SD cards.  I have lots of them, 8-16GB and 5MB/s.  Too slow to flash images, and too slow to run on it.

So, I've been shopping around for a fast microSD card.  What I don't understand is,
    - some U1 cards are faster than U3 cards.  This means, I can't just search for "U3" cards.

- Do you know why U3 cards are slower than U1 cards?
- Any brand recommendation?
    - Canada Computer has lots of "Teamgroup".  Are they good?  They are new (to me).
    - Of course, can't go wrong with Samsung.  But, not at $20 range.
    - no Kingston.  All the dead cards were from Kingston.