I think beginers should learn the 8052 families because it is a standard microcontroller with all these fancy addressing modes, reliable and widespread.
After that they should upgrade to PICs and AVRs.Learning new concepts and techniques.
Counting the number of DSTV cards using pics and avr cards makes them most used microcontrollers ever.
Just calculating on me and my friends I have 8 pic cards and 1 avr card for the satellite.
I also have 2 card programmers.
small pics have 33 instruction sets, so it is very easy to learn them all and understand the program.
So weather to use PICs or 8052 depends on many factors:

    1. Personal preference and experience.
    2. built in peripherals (EEPROM, RAM size etc).
    3. Volume of production.
    4. development tools availability.
    5. cost and availabilty.

regards
Mahmood