I looked into many microcontroller options because I want to be able to use a fully functional programming language with microcontrollers. I don't want to be hobbled by various proprietary versions of BASIC. Plus I wanted to be able to tap into the vast amounts of freely available code out there and using C is the best way to do that.
These are the three that most interested me: Microchip PIC, Motorola 68HC1?, and the Atmel AVR 8-bit RISC.
GNUPIC is the best resource for free software for the PIC chip. Its a bit disorganized, but the info is there.