Yet another PIC fan here (can you understand now why Microchip OWNS the microcontroller business even after all these years?
), and I have been using PIC processors for three years now at my co-op with an awesome robot controller board we whipped up and had made at a PCB prototyping house. The board has a number of different shift registers allowing for hundreds of digital outputs along with a couple bytes of directly-linked pins for high speed digital IO, along with an ability to directly connect to some of the more interesting pins that come out of the micro (i.e. input captures, counters, etc.), some 8255's for general purpose digital input, and a pair of RS-485 transciever pairs for communication to up and downstream devices on the production line.
The board is set up to use the 18F8722 as it's microcontroller, same as is in the FRC controller. It's a fantastic processor, lots of internal peripherals to keep you busy, just wish it had DMA sometimes. But, who can argue with a cheap processor that can handle communications AND run two step-driven axes at 12,500 steps/second with interpolation.
This processor is availble on the HPC Explorer board from microchip as well, and can be used with the on-board bootloader it comes loaded with if you want to go that way, or you can get and ICD. I believe the PICkit2 programmer will program the 18F's too. (just search microchip's website with any of these names if you want more).
A new processor I've recently started working with is the 33F series of digital signal controllers. Awesome pieces of hardware, running at 80MIPS... very nice library of single-instruction math functions too (namely, fractional divide, square and accumulate), DMA capable, CAN compatible, some even have dual analog converters if I remember right. Just a few months ago I finished writing the low-level hardware driver for a 33F to run a 128x64 graphics LCD. My first project ever to have a TV to talk to the world with!
Well, besides that huge LED segmented display on our robot this year...
Hope that helps... post if you have questions.
-q