Jay.slovak said:
Code compactness and execution speed, variety of peripherals, different PICs available alowing you to choose one that will fit your needs, low power consumption, great support from Microchip (Datasheets, MPLAB, Samples), and many more.
in terms of execution speed SiLabs offer the fastest 8-bit microcontrollers in the world (upto 100MIPS) which are based on an 8051. and if you visit SiLabs website
https://www.silabs.com/tgwWebApp/public/web_content/products/Microcontrollers/en/index.htm you will find 8051s that have lots of peripherals.
and as far as variety is concerned, 8051 is available from hundereds of manufacturers each different from the other.
im not saying that 8051s are superior to the PICs. my point is that it doesnt matter which microcontroller you choose. you can finds ways to do anything with one microcontroller which the other can do aswell.
i hope that helps