There's 2 choices that instantly comes to mind for me, and I'm absolutely amazed by the lack of mentions these two pairings have.
First of all:
I'm including them with the D-Generation X pairing, both because it really just looks better, and because not only are these two guys best friends, and worked for years together in D-Generation X. But they've also had some amazing matches spanning over a periodic 2 years feud more or less.
These are the two guys that put on an absolute war whenever they would face each other in the ring. At the Royal Rumble in 2004, at Summerslam in 2002, Survivor Series 2002, Armageddon 2002 and especially at Wrestlemania 20.
And on top of that they had some absolutely amazing promos alongside each other during times with D-Generation X, which I think definitely also counts as a part of chemistry, the very fact that they could play off each other so perfectly, to create such great promos and matches.
And my second choice, which surprises me even more:
60 minute Iron Man Match anyone? Nobody remember that? While a lot of people seem to agree there were a lot of rest holds, and it wasn't even the greatest Iron Man Match by far, I think that it definitely deserves a mention to the fact that these guys had great chemistry. Shawn and Bret might have had their problems from time to time, but when they would square off inside the ring, there was bound to be something epic going on. Even back when Shawn wasn't a main eventer yet, he was still tearing down the house with Bret Hart at places like Survivor Series 92.
These guys are two of the greatest in-ring performers of all time. They would always go out and perform at the top of the crop, solidifying themselves every single night as legends. And every time they would square off, there was a very special feeling about it. And I think that definitely has a big play in the whole fact that Shawn and Bret had an amazing chemistry in the ring.
First of all:

I'm including them with the D-Generation X pairing, both because it really just looks better, and because not only are these two guys best friends, and worked for years together in D-Generation X. But they've also had some amazing matches spanning over a periodic 2 years feud more or less.
These are the two guys that put on an absolute war whenever they would face each other in the ring. At the Royal Rumble in 2004, at Summerslam in 2002, Survivor Series 2002, Armageddon 2002 and especially at Wrestlemania 20.
And on top of that they had some absolutely amazing promos alongside each other during times with D-Generation X, which I think definitely also counts as a part of chemistry, the very fact that they could play off each other so perfectly, to create such great promos and matches.
And my second choice, which surprises me even more:

60 minute Iron Man Match anyone? Nobody remember that? While a lot of people seem to agree there were a lot of rest holds, and it wasn't even the greatest Iron Man Match by far, I think that it definitely deserves a mention to the fact that these guys had great chemistry. Shawn and Bret might have had their problems from time to time, but when they would square off inside the ring, there was bound to be something epic going on. Even back when Shawn wasn't a main eventer yet, he was still tearing down the house with Bret Hart at places like Survivor Series 92.
These guys are two of the greatest in-ring performers of all time. They would always go out and perform at the top of the crop, solidifying themselves every single night as legends. And every time they would square off, there was a very special feeling about it. And I think that definitely has a big play in the whole fact that Shawn and Bret had an amazing chemistry in the ring.