Advantages of ATmega32

What are the advantages of using ATmega32 than other microcontrollers? Is it better than PIC, ARM, and 8051?

It depends... Firstly, you have to know what you want from the microprocessor.

In general:

PIC:

• Old architecture. This means it's either expensive or slow
• Targets only low end market (less than a few MHz)

• There's a lot of code written for it

ARM

• Scalable
• Fast/cheap

ATmega is somewhere in between.