The case for Piper Chapman, and somewhat for Larry
I think that Piper Chapman is the appropriate center for Orange is the New Black, please hear me out.
The strength of Orange is its willingness and ability to explore female characters that are marginalized through exposing the intersections of their oppression. It allows its characters to be victims and perpetrators both (victimized and victimizers, to different degrees). It allows them to be dangerous, and vulnerable, and kind, and mean. In short, this is a show that lets its women be human, that recognizes the precariousness of their existence both inside and outside of prison, and does not shy away from the high price one pays for being different from the perceived norm.
This is where Piper comes in, she is the perceived norm (white, beautiful, educated). Through Piper Orange can contrast privilege and margin within the ecosystem of the prison. Then again, through Piper Orange can show Piper’s own oppression and dehumanization in contrast to her own privilege; Piper is prosecuted for being a prisoner, for being a woman, and for having a fluid sexuality (especially by Healy). In showing both how Piper is prosecuted and privileged, Orange puts emphasis precisely on how intersections of gender, class, race, sexuality, age etc. affects power dynamics. In particular it drives home the point that privilege is not the same as the complete absence of oppression.
Then there is Larry. And Polly. And Pipers parents, and her brother. We have some white archetypes on display here; the luxury hippie hipster (brother), the wasps (parents), the neo-bourgeoisie (Larry and Polly). All of these archetypes represents their own spheres of white privilege, all of which are contrasted with Piper’s oppression, and even more starkly so against the rest of Litchfield's inmates. The presence of their respective ridiculousness and apparent self-involvement works to expose the intersections of relative-privilege and marginalization much more clearly than would be possible without their presence. In placing Piper in the center Orange constantly destabilizes the naturalness of privilege, both in her relationship to white archetypes, and especially in relation to her fellow inmates.
Seen from this perspective, the instance of the This American Life spoof and Larry’s general moon-ness to Piper’s (and the prisons) sun becomes quite interesting, in that it can be read as a metaphor for how “white” culture exoticize and fetishize the non-normative, a practice that results in the kind of clichés, simplifications, and dehumanizing representations that Orange is trying to move away from.
Read from a character perspective, Larry's response to being called out on his moon-ness is telling in another way. People sure can walk on the moon Larry, they can walk aaaaall over it.