The main character is one of my least favorite characters in the show.
why?
If I didn't like her, the show wouldn't even come close to being worth watching.
Mainly because she's whiny and holier-than-thou. She thinks she's better than most of the people in there and doesn't appear to take the time to realize that not much separates the stories of how they got there vs how she got there. Which is really one of the cruxes of the show, because of course on the inside there's nothing separating them. And then the cast of characters getting flashbacks shows that circumstance is often the reason people end up inside - and Piper really isn't better than them at all.
She is occasionally resourceful and badass, I don't hate her. Just don't find her the most interesting.
I think she is largely there as a device so that the middle-and-upper class audience of the show can project themselves better into the scenes. Without her perspective, a lot of the situations would feel pretty alien to most viewers.