[wiremine]

The thing with microcontrollers in general is that they tend to come in MANY variations to support all the various use cases out there. So, it really comes down to your use case. Once you have that figured out, it's much easier to pick an ARM platform.

Most of the time people are taking about the M-series, so you want an M0, M3 or an M4. I'd recommend an M4 if you don't have something specific in mind.

The STM discovery series is an easy place to start:

https://www.st.com/en/evaluation-tools/stm32-discovery-kits....

I'd also recommend checking PlatformIO: It's a great project that streamlines development and abstracts a lot of the details:

https://platformio.org/

To answer your question directly, here's a good start:

https://developer.arm.com/ip-products/processors

And here:

https://en.wikipedia.org/wiki/ARM_Cortex-M