If I started to make a new project I would choose some of the more powerful PIC:s today. Of course they are a bit more expensive but they will give you much more possibilities when you find new things you want to do down the road. This will also help you to do the next project faster since you have already code and schematics that you can use to get started with.

If you plan to write all code in PBP it does not really matter if you go for 18 or 16 series.

I think PIC18F4550 (USB is always useful)

16F877A is also a good choice since you can, if you need more memory, drop in 18F452 or 18F4620 on the same footprint (they share the same pinout for the PT versions at lest)

I guess when your project is finished you will have a giant display, field upgrade using bootloader and many many more things you never planned to have from the beginning. So if it is not a matter of cost and availability I would say bigger is better.

But then your teacher will ask why you didnt choose a cheaper PIC for such a simple job... they will always ask this and that.

I would not choose a SMD package that has more then 44 pins. 44 pin packages are still possible to solder by hand.

If you dont have a need for serial communication and want to reduce cost I would choose a PIC with a built in oscillator.