Arduino Uno and Nano

16 MHz, 32K ROM, 2K RAM, 2K EEPROM.

Arduino Mega 2560

16 MHz, 256K ROM, 8K RAM, 4K EEPROM.

ATmega1284

< 20 MHz, 128K ROM, 4K EEPROM, 16K RAM.

ATmega4809 boards

20 MHz, 48K ROM, 6K RAM, 256 bytes EEPROM (?!)

AVR DA and DB series boards

< 24 MHz, 128K ROM, and 16K RAM