For those who needs something more beefy, check out https://www.nxp.com/support/developer-resources/evaluation-and-development-boards/freedom-development-boards

For those who needs something more beefy, check out https://www.nxp.com/support/developer-resources/evaluation-and-development-boards/freedom-development-boards/mcu-boards/freedom-development-platform-for-kinetis-k66-k65-and-k26-mcus:FRDM-K66F https://www.nxp.com/support/developer-resources/evaluation-a... They are about 60 USD per board, though if you want only the chip for a final product, it will become much cheaper. We use these development boards in combination with freeRTOS (bare C based) for lots of projects in our lab that require high sampling rates (e.g. 8 analog sensor readings at 1 kHz) motor control loops etc. There is a very good blog on these chips at mcuoneclipse.com