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

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.