Final Analysis:
In order of strength
1) Yoda
2) Mace
3) Emperor Palpatine
4) Anakin Skywalker
5) Obi-Wan Kenobi
This is proven by this movie.
Yoda is the man. Palpatine constantly initiated his force attacks from a distance. He matched Yoda in sword play only because Yoda is a weaker sword fighter. NO ONE can defeat Yoda in Force knowledge. No one. Everyone who knew Yoda knows that the only way to have a chance with him is through a sword fight. It's proven in Attack of the Clones with the Dooku duel and now in Sith.
Mace is the strongest sword fighter. He doesn't use a lot of excess movements. To be honest, a true master doesn't need to use a lot of moves. One can be deadly enough. They know they can't play with Mace because one move might be all it takes. Fighting Yoda on the other hand requires a LOT of swordplay moves because of his flurry of attacks in battle. But Yoda is not the best swordfighter. But he is swift.
The rest doesn't need to be explained. Anakin obvious had the sword fight the whole time, but Obi taught him so there was the issue of the pupil succeeding the master, as any good pupil WILL do. I think that Obi would have eventually run out of moves. He got lucky.
Palpatine is very knowledgeable in the Force AND a decent swordfighter. But outclassed. If Yoda and Mace attacked him, he would be dead. Period. Palpatine could not even defeat Mace one on one. Mace could NOT have deflected the force bolts. He isn't centered enough to be so. He is more emotional and physical power. To be honest, Mace would have lost if he DIDN'T have his lightsaber. If it was a one on one force battle, Mace would have lost, period.
Out.