PIC programming is a bit dated, but you can do it. Even with an Arduino it is hard as the math is very relative, and I have seen five very competent programmers try Arduino, Teency, and maybe another one or two micro-controllers. They all ended up quitting on it or changing it to use an actual flight controller for stabilization.
If you want to program it yourself you can always use a regular flight controller for stabilization and something else as a MITM.
If you insist on doing it all yourself then I definitely suggest getting a 15$ flight controller to use to verify that all of your hardware works before you start trying to program a flight-controller with potential problems in your hardware, as there are hundreds of possible problems.
I don't say this to question your skill or to put you off from this idea, obviously if you have experience with PIC programming you have been doing this for a little bit and have some experience, but be prepared to learn a little physics as you don't need to be a good programmer for this type of thing, nothing complex on that side of the coin; but there is a lot on the mathematical and physics side of it.
I'd suggest the
PIC16F877a.