I have experience with assembly and C programming for microcontrollers, but I'm not familiar with the various MCU and DSP families offered by today's companies. (eg: Texas Instruments, Atmel, Renesas)
I'd like to know about the good microcontrollers / DSPs, and what its like to develop with them. Please summarize your understandings about the various MCU / DSP families, one family per answer.
It would be very interesting also if you detail what is(are) the main application(s) for this(ese) microcontroller please.
(This is a "community-wiki", so anyone with >100 reputation can refine and improve answers)