If you're buying your first set of chips, go with the 16F88. It's a good all around chip and has twice the memory of the 819, supports upto 7 10-bit A/D converters. It also includes hardware support for RS232, I2C, and 1-wire buses. Your other option is to go with one of the 18F chips. They offer a simpler programming model (no bank switching) and are supported by the free version of the Microchip C compiler.