Personally I think ARM is all round better, faster and cheaper, but I have been working with ARM chips since 1999 so they are well inside my comfort zone. I think it's amazing how many functions have been crammed into AVR firmwares, but if you want to do things like ethernet, run a web server, run non-cartesian geometries, ARM chips provide a lot more scope for expansion. You could also do things like run a 320x240 touch panel TFT display instead of 20x4 LCD.
I have never run an AVR based controller, I have only used ARM based ones, so I am fully committed to the idea :)
I have never run an AVR based controller, I have only used ARM based ones, so I am fully committed to the idea :)