CM Punk vs Rey Mysterio Jr was actually a great feud. It was nice to see someone who brought out the best in Mysterio again.
Dolph Ziggler vs Kofi Kingston was wonderful. Those guys had some amazing matches together.
Although it was very short, one of my favorite feuds was Chris Jericho vs Evan Bourne. Their matches were great.
If I had to choose just one feud, it wouldn't be easy. How about, as Mike The Bike basically put it, Miz vs WWE! I have enjoyed everything Miz has done this year. It didn't matter who his opponent was, Miz kept my eyes on the screen.