Choosing the right MCU

Hi,

I'm looking for an MCU for a central control unit (need
SPI+I˛C+UART+some I/O). Amost every manufacturer has a suitable MCU
for this application (Atmell, microchip, TI, ST, ...).

But what i'm looking for is
1) An MCU that can easily be programmed in circuit (few extra
components).
2) A FREE C-compiler with >4K program space. (most important)

Any ideas ???

Greets,
Johan