So you've already outgrown Arduino's most beginner-friendly board, the Uno, and are looking to move on to bigger, more exciting projects. In that case, the Nano family might just be what you need.
Arduino is being acquired by Qualcomm subject to regulatory approval for an undisclosed sum. Qualcomm Arduino introduces a new UNO form factor board, the Arduino UNO Q, which features both a STM32 MCU ...
Arguably, the ATmega328P is being left behind as ‘the Arduino processor’ because Arduino’s are following the rest of the world and going 32bit.