STM32F303RDT6 vs ATSAM4S4C: Feature Comparison, Price, Ecosystem, and Support

Hello everyone,I was looking for a general purpose Cortex-M4. I did a quick search in Farnell's site and I noticed that microchip's SAM has become cheaper enough and I was wondering what is the benefit to choose STM's chips instead of Microchip's?To be exact I will add an example here:ATSAM4S4C can be found at 2.59 GBP at 100 pieceshttp://export.farnell.com/microchip/atsam4s4ca-au/mcu-cortex-m4-256kb-120mhz-lqfp/dp/2396714?ost=Atsam4s4c&iscrfnonsku=false

In contrast,STM32F303RDT6 can be found at 3.01 GBP at 100 pcshttp://export.farnell.com/stmicroelectronics/stm32f303rdt6/mcu-32bit-cortex-m4-72mhz-lqfp/dp/2488300?ost=Stm32f303rdt6&iscrfnonsku=false

Why someone would choose the one instead of the other?

Hi George,
I haven't looked specifically at those two chips (the last project where I specified an ARM, we used NXP) but several things to look for.
Do you have an existing support relationship with either vendor?Does either chip stand out in terms of features and pin configuration (i.e. can you actually use all the features you want)?
Relative to the above, is it easy to find this information in the datasheet?
Is there an active users group for either or both and what do they have to say about how easy the parts are to use?Are there evaluation boards, compilers etc specifically targeting either or both?Once you have answers to the above, you can decide based on what is most important to you. If they both seem equal then just pick which one you like.

FYI- Microchip is pretty generous with their samples.  You should be able to get at least three of their parts at no cost.
-Rick  

GeorgeSomething you may want to consider is that the SAM range is in fact the Atmel product as a result of Microchip's acquisition of that company. I have only been burned once by Microchip discontinuing an IC, so I think supply will not be an issue. Prior to the acquisition, Microchip never had any ARM processors, and Microchip did lay off a bunch of Atmel employees. My experience with Microchip support has always been positive, but you have to wonder if there is still the expertise to answer difficult questions on Atmel parts.On the other hand, the one experience I had with ST support (not micros) left me thoroughly unimpressed.