After the Mega 256, what is the next most powerful Arduino board?

Hello, I have been using the Mega 256 but I don't use all the pins. What is the next most powerful board that offers "just a little bit" fewer pins but smaller in size?

https://www.arduino.cc/en/Main/Products.

Take your pick, Zero might fit the bill.

Or look at Teensy USB Development Board

What is the next most powerful board ..

Two Questions:
1. What is the accepted definition of a most powerful board?

2. Do you have your own (if any) definition of a most powerful board?

If you want to stay in AVR-land, there's no official board between the Uno and the Mega2560. There are unofficial boards (with good support via hansibul's core) with the ATmega1284p, and I think the ATmega2561 with more pins than the atmega328p but fewer than the 2560.

There are also all the "faster" arduinos like the Zero and other SAM based boards. These are pretty well supported, and can do computations faster, but they're 3.3v (so you need level shifting to interface with 5v stuff) and the library support isn't quite as good.

Word of terminology: "powerful" is ambiguous - most poeple take it to mean processing speed, not number of pins. A mega2560 is actually ever so slightly slower than a 328p, due to differences in certain instructions to support the larger flash address space.

Wonder why Atmel didn't step the AVR architecture up to 16 bit (databus) instead of "leaping" to 32 bit ARMs?

Isn't that xmega? They didn't take off the way the atmega line did, as far as I can tell.

Yes! It is!

TNX! Didn't know that, will investigate.