8/16 bit microprocessor for hobby project
Maybe you should let go of the idea that for small hobby projects 8-bitters are always the best solution. Nowadays 32-bitters, esp. ARM, are everywhere and they have become serious competitors for the often older 8/16-bit parts, both price-wise and toolchain-wise.
Besides, in your comment you mention 512 KB internal memory, and you won't find that easily on pure 8-bitters; they tend to have a 16-bit address bus which means 64 KB maximum.
If you think an ARM may suit you, you may have a look at mbed:  


  "This mbed Microcontroller is based on the NXP LPC1768 with an ARM Cortex-M3 Core running at 96MHz, 512KB FLASH, 64KB RAM and lots of interfaces including Ethernet, USB Device and Host, CAN, SPI, I2C and other I/O."