Nigel defniitly most popular by numbers, but that doesn't mean everything. Even the little I know about PIC architecture, the register banking, the clock division. Especially for ASM equvilant code for an AVR and PIC the AVR usually will win out on readability and simplicity to someone that hasn't learned the complexity of a pics architecture. AVR's can get complex, but their core architecture was developed after PIC's and it has many advantages to the newbie, and trust me. I have NO problems finding information on the net about AVR's between AVRfreaks and general googling there are just as many informative resources. Most popular does not always mean most efficient or most easily understood. That's why I recommend AVR's to newcomers to strongly, the initial learning curve is a LOT less steep, especially for ASM programming.