AVR Freaks

Just Add 

A MSP430 is a 16bit chip not 8.

So if the MSP430 is to small I also would go for an ARM, which I don't know that will really depend.

add:

One thing both MSP430 and AVR are good compared to ARM is low power, and sleep power, but newer ARM's are getting better.

Have you tried the MCU selector: https://www.microchip.com/maps/M...

Only you know exactly what kind of specs you need.

edit: yeah, I'd go for 32 bit for these specs. They are faster and cheaper, this means the manufacturer wants people to use them. Here are a couple from our sponsors:

https://www.microchip.com/wwwpro... (PIC32, i.e. MIPS32 architecture, I never used them but the specs seem nice)

https://www.microchip.com/wwwpro... (and this one is a Cortex-M0+. From my limited experience, the SAMD are nice chips, a bit complicated to configure, but that is kind of inevitable with 32 bit chips)

@OP - have you looked at why you are running out of code space?  Can you just optimize current codebase and get more free space?  That way you don't end up with orphaned hardware with old CPU ?

I was actually responding to OP saying

Basically, I have a suite of products that use the MSP430F1611IPM and MSP430FG4618. I am running out of code space (10 bytes left) and looking at swapping out the micro's for new bigger devices.

If he changes CPU then his suite of products now has a lot of "version 2" that is incompatible with version one.  I don't know how many products he has out there or if he has to support past customers.  If he does have to support old customers then maybe code space optimizing is a better idea.

If you are learning a new uC, ARM cortex M0 is the best choice. M0 has alot of reach and available from multiple suppliers each having slightly different offerings. M0 is about $1, so you are not paying a premium over an 8/16 bit uC.

KEIL for ARM is free for upto 32KB of code and it supports the entire range of M0/M3/M4/M7 devices, so if you wanted to stick to the same IDE for each project then KEIL is a good choice.

In the future you can easily transition to M3/M4 and arguably M7 if you need more horsepower while keeping the same IDE.

Prior to ARM cortex, there was alot of complex configuration you had to do for ARM7, but nowadays with cortex the configuration is much less complex though still more complex than say AVR. IMHO the complexity of ARM Cortex is just about perfect, any less complex and it would gimp the available options for experienced developers, any more complex and it would put up too many roadblocks for new developers.

It is not all about the uC core, the cortex peripheral set is also much more powerful WRT 8/16 uCs. For instance, I think AVR ADC is ~50ksps max, at the max sample rate the AVR would be almost 100% occupied just moving data from the ADC registers to RAM, if the ADC sample rate was any higher it could not be taken advantage of by AVR. ARM cortex M0 ADC is in the 250ksps range, the M0 core can keep up with shuffling data from the ADC resister to RAM at the max sample rate though the M0 would have nothing left over to do any processing of the ADC results.

GPIO reading and writing on ARM cortex is often very slow compared to other uCs, that is the only legit beef I have with ARM Cortex.

If you are looking for a good M0 platform that is least complicated and dirt cheap I would recommend the Nuvoton line of M0 uCs, it looks to me like Nuvoton just got a default template from ARM and made their M0 chips with little to no modifications which to me is a good thing when starting out with M0. 

I did not know there were new AVRs with upgraded ADC peripherals. The accumulator I think is only useful if you want to oversample, otherwise you are using pure CPU power to shuffle ADC data around.

I have never looked at XMEGA, it does not surprise me that it has DMA. DMA on M0 is quite common.

My general observation is that more powerful the cores tend to bring in more powerful and more complex peripherals, that was what I was trying to get at. My ADC example might not be the best example of that if you throw DMA into the mix.