Instead of looking for a completely compatible alternative, you should decide what are the features and peripherals you need. Eg. you may decide that you need a certain number of pins, a certain number of ADC input pins, a certain number of PWM modules. You may need serial communication. Like this, choose what you want and choose a PIC that fits the requirements. Then, you'll get a better choice of the PIC to use instead of looking for a PIC that is completely similar to the HC908.
A few common PICs that have most peripherals are:
PIC16F690, PIC16F877A, PIC16F887, PIC18F2550, PIC18F4550, PIC18F458, etc
Hope this helps.
Tahmid.