I have a different method of selecting MCU's. I check the programming language I can use first, then check for the availability of free full-featured software (toolchains), then narrow down my chip selection (by IO pins, flash, RAM size etc).
I've used C all my life (work and previously at school) so it's my #1 language of choice. I've extensively used the GNU toolchain so that is a must for me. Now the hard part, the chip. Some of the well-known chips (Basic Stamp, PIC) are not supported by the GNU C toolchain (or maybe I'm just not searching hard enough). I think Microchip does have a crippled C (student version) compiler for the PIC, but that's it.
This eventually led me to the AVRs, nice little chips, and you can grow with them both budget-wise and functionality-wise. Freely available IDE which can use the GNU toolchain, and also freely available simulation S/W (VMLAB), and most importantly there are good forums out there (avrfreak.net) where you can find valuable information.
HTH. Good luck on your search.