Well,
PIC16F84A (don't tell anyone - I still have a few of these hanging around, but never use 'em)
PIC16F628 (Got a few tubes of surface mount, on a deal)
PIC16F628A (easy to use, simple projects, adapt 16F84 examples on the web to this easily) I grabbed 25 of them last time...
PIC16F88 (Have a couple, these are great, wish I'd grabbed 25 of these.)
PIC16F877, 877A (Still have a few of these around...)
PIC18F454 (Have a few, and also have an 18F458, which has more program memory)
PIC12F683 This is a 'sweet-heart' of a little chip... grabbed 25 last time...
PIC10F202 I wanted surface mount parts, but they sent DIPs.
the SMT part is like a spec of dust, with 6 pins on it!
PIC18F1320 - good small 18F chip
PIC18F2620 - like above, but 28pin skinny dip more resources
PIC18F2250 and PIC18F4550 for USB, of course
PIC18F8720 18F8722 I have a few of these HUGE things with 2 USARTs, 128k of program memory and an external memory bus... don't want to waste them on small projects
Have a few dsPICs but haven't really had time to put them through the paces...
Microchip also has some very interesting peripherals I'd love to have around to play with...