If you don't want 8051 chips, and don't like AVR or PIC, then you can also find ARM chips at under $2 and with quite cheap debugging tools needed. The bad thing is that the Keil compiler is expensive, so don't make the move from 8051 unless you really need some features or capabilities from an ARM chip. There are gcc for ARM but without the Keil debugger, that may not be an option.