For my final year project I ended up experimenting with ATxmega16e5 microcontroller, after major step backs with TI ARM microprocessors (don't get me wrong ARM is very powerful).
At the first glance these new xmega series uC are quite impressive. 32MHz internal clock, incredibly fast ADC (16e5 can have up to 300ksps), 12 bit adc, DAC, two or more USARTs and list goes on. Moreover you are able to use tools you're familiar with, when it comes to program AVR family micros, providing you have programmed AVR family before. I have yet to test full capabilites of the new xmega series, but I'll write posts about individual modules, like ADC, USART, DAC etc.