Short answer, neither.

Thanks! I had been hoping to hear from
you specifically on this stuff.

For now, I've gone with the Atmel 328 + Arduino, because my needs are rather simple. I just want an easy and low-cost way to string some GPIO lines off the end of a serial port, with maybe a teensy bit of smarts in the device.
I'm thinking LCD interface + keypad interface, in a single device. That means 7 GPIO lines for the (text) LCD, and as many as five more for the keypad. Or fewer, if I can get by with using more resistors and less scanning for the keypad.
Cheers!