Seems to be a bit of Atmel bashing going on here! I think it pays to remember "no one is innocent, but some are more guilty than others"!

Just my 10cents worth.....

I personally detest using the PIC, but I do appreciate its simplicity and what you can do with it. It is the sort of cpu I would design from scratch if I had to have a quick & dirty (cheap & cheerful??) processor to stick into a fpga - however nowadays you have a choice of a variety of cpu cores already done for you. The designer must've thought he did a wonderful job extracting the maximum functionality out of minimum hardware - and he did.

However, I've done quite a bit of assembly programming on both 8051's and AVR's over the years. Initially I was quick to dismiss the 8051 as 'old' but after writing a bit of code for the AVR, you realise that the 8051 seems to have the right mix of instructions for controller applications - you're rarely at a loss on a useful instruction and if so, a couple of instructions will do what you want. The stack size limitations of the 8051 have rarely caused me problems - I did have grief squeezing some code into a at90s2051 many years ago and I was counting stack bytes as well as code bytes to get the thing to fit and work!

I can also say I enjoyed programming the Motorola 68xx series - the HC08's are quite cheap and spritely these days but these don't seem to appear on the hobbyist radar. Pity, the free tools are quite good.

Then we come to things like the ARM. These are a general purpose processor so bit twiddling is not native to them like in the 8051, so writing controller code seems labourious. To get around this, the manufacturers add hardware to emulate the bit operations for the port pins. It harkens me back to the Z80! Most of the time these days I let the C compiler do the work so I don't need to know the intricacies of the architecture - however, I am finding I need to do a little investigation recently!

Ultimately, what processor you choose is what you're comfortable with. The software tools are probably more of a deciding factor - good tools make your job soooo much easier. The end result is that it has to work, otherwise you're just polishing a turd.