Recently I've been heavily going back to PICs (8,16 and 32 bit) after a few detours into NXP ARMs in recent years.
The main reasons being, in no particular order :
* same programmer for all devices, and Pickit 3's standalone programmer-to-go mode is absolutely ideal for production programming, either on a jig or handheld - I can just give it to a subcontractor and tell them to connect it, press a button and check the light goes green.
* Same IDE for all devices, and very similar compilers
* Similar peripherals from 8 to 32 bit devices
* I can order preprogrammed parts from Microchipdirect for a few pennies and a couple of days extra.
* wide range pf packages from DIP to QFN
* Pin mapping, especially on PIC24 - pity this is a lot more limited on the PIC32MX
* Internal oscillators that are accurate enough to do UARTs - it has taken some manufacturers a while to catch up with this.
* always available.