How's the open toolchain support with those chips?

I've also heard good things about NXP's Cortex-M chips - apparently they let you map peripherals to whatever pins you want, which sounds neat. And TI's MSP432 chips apparently have fantastically low power consumption for their performance. Atmel's SAM chips look less promising, with minimal peripherals besides a weird common communication bus that seems to handle things like I2C/SPI/etc, if I'm reading the datasheets right.

Does that sound right? It'd be nice to learn about all of them, but there are only so many hours in a day.

I used one of their Cortex M3 parts on a project a while ago that needed a large number of SPI ports to drive strings of LEDs. Was very easy to get the initial POC working, and their IDE software worked surprisingly well.