The Sue/Kelly/Rich feud was amazing! It started with Sue/Kelly/Rich making the alliance and Sue/Kelly dealing behind Rich's back to get rid of him at the end. There was always this little feud between Sue and Rich because Rich saw her as a dumb hick and she saw him as a pompous ass, but they worked together because they knew they needed each other. Then it all blew up when Kelly started becoming too friendly with the Pagongs, causing Sue to turn on Kelly and then it became Rich/Sue vs Kelly, and it culminated in the epic jury showdown where Sue showed her true colors in hating both of them, and the nasty tongue lashing she gave Kelly made it an epic feud. And then of course it continued into All-Stars where it was more of a friendly rivalry until Rich rubbed Sue naked and caused that blowout.

Honestly, it's one of the top feuds ever. It started in the beginning of the season and Sue managed to start off fucking around with Kelly by voting Sonja instead of Rudy at the first vote, and yet ended up then working with her and Rich to later just keep the blood boiling. Light years ahead of feuds you listed like Parvati/Eliza, Jenna/Heidi vs Christy, and Danni vs New Nakum.