I agree with what
@Frozen said above, about NY potentially not lasting this long without Ramona on the show. It certainly wouldn't be the fan favourite without her, at least. As so much of the action revolves around the fall-out from her bullish mis-steps. Without Ramona, it's fair to say that none of the core cast of Sonja, Luann, Bethenny or Dorinda would have lasted so long. She unwittingly feeds them storylines. She can't help herself.
To me, there are four stages of Ramona throughout this show's run.
In the beginning I hated her. A loud, whiny, obnoxious irritant who used to see right through the bullshit of my faves - Jill and Luann - and wasn't afraid to set them straight on camera. And she was always, always right about them.
Then from season 4 onwards, I began to really warm to her - thanks mainly to her pair-up with Sonja. For the next few seasons she was a lot of fun to watch, really riled up all the new Housewives who'd joined the cast, and didn't seem to care one bit. The cast trips in particualr being a highlight.
Then there was the birth of a new kind of monster - from season 7, when Bethenny returned. The power struggle, the desparation for Bethenny to acknowledge her as an equal in business/clout (which is never gonna happen, and which kills Ramona still). Ramona was single again, she was attempting to climb society, and she was also trying to (and succeeding in) reverse the aging process. The glow-up brought out the best of her looks, and the absolute worst in her personality. New highs and new lows. I loved her around this time too.
And then there's the last couple of seasons. She's checked out, she doesn't really view these women as friends anymore, and she's just turning up for the cheque. Whereas before, RHONY showed her life, now it just feels like we're seeing her show up for a job, and counting down the seconds until she can return to her actual life with her actual friends. All 60 of them.