Brand: PNY
Type: Micro SDHC
Size: 16GB
Class: 10
Axoloti says: write BW : 186 kB/s
Axoloti says: read BW : 1440 kB/s
Brand: SanDisk
Type: Micro Ultra SDHC I
Size: 32GB
Class: U1
Axoloti says: write BW : 495 kB/s
Axoloti says: read BW : 2016 kB/s
The downside of that SanDisk one is that it's slightly thicker than most Micro SD cards I've seen and just barely fits into the slow on the axoloti. I've also had it get stick in the adapter that came with the PNY once, badly enough that I needed pliers to get it out. So that's something to be aware of if you're shopping for one.
EDIT: when using wave/play to stream audio from the SanDisk card I experience the bug others have reported where the Axoloti immediately crashes.