hey, first question i will probably get flamed for but i find ASM easyest to use, mainly cuas its risc, u just have 36 (ish) instructions, and once u get over some conceptual difficulties it makes life much simpler as long as u don't have to do not arithmetic maths.
16 series PIC realy depends on the rest of ur application some have PWM modules built in, which would make coding ur project a snip but might be un-necisserry if all the chip has to do is make PWM (555 would be easyest!).
In short could u say a little more about ur project, or just pic a 16 with a PWM and the datasheet tells u how to use it in ASM