Borbarad
Advocatus Diaboli
Wow. I have to cast my judgement here, and that would be, that you people do terrible suck, each side for different reasons. Ignoring the pointless feat war business going on here ("But Sidious ruled a galaxy..." Who the hell cares?), lets break this fight down for you.
Known combat-related feats
Yoda and Obi-Wan
[list]
[*]various instances of telekinesis, ranging from tossing humans around (Kenobi in Revenge of the Sith) to the levitation of seemingly massive metal structures (Yoda, Attack of the Clones and Revenge of the Sith
[*]precognition, which allows Jedi to react extremely fast on attacks directed at them
[*]force enhanced speed, allowing Obi-Wan to handle an opponent wielding four lightsabers (Revenge of the Sith) and granting Yoda the ability to deflect roughly 40 blaster bolts in round about 3 seconds (Revenge of the Sith)
[*]lightsaber skill
[/list]
Saruman and Sauron
[list]
[*]various instances of telekinesis. Saruman has been shown to tossing Gandalf around like a ragdoll (Fellowship of the Ring), while one could argue, that Sauron's mace emits some telekinetic waves in order to throw people around.
[*]if you don't want to accept the latter point, one would need to add "superhuman strength" to Saurons abilities, able to toss dozens of human beings in full armor around like ragdolls - which is probably true regardless of the first argument, because the guy is a freaking giant that towers above the elves and men alike.
[*]mind-control over a rather huge distance (Saruman mind controlling Theoden in The Two Towers)
[*]influencing people by talking to them (implied for Saruman in The Two Towers and Return of the King)
[*]throwing fireballs (Saruman in the Return of the King extended cut)
[*]influencing / controlling the weather, specifically lightning (Saruman in Fellowship of the Ring)
[/list]
Those are the feats that I can list on top of my head. One could make the assertion, that Saruman does possess the same powers Gandalf has demonstrated throughout the series. That would be:
[list]
[*]creation of magical shields against physical/magical attacks (Gandalf fighting the Balrog in Fellowship of the Ring)
[*]dealing damage to inanimate objects almost at will (Gandalf destroying the bridge under the Balrog in Fellowship
[*]extreme fast reaction time (Gandalf deflecting arrow shot at him by Legolas in The Two Towers)
[*]ability to work several magical effects a the same time (Gandalf upon meeting the trio of Gimli, Legolas and Aragorn heats up Aragorns sword, causing him to trop it, blinds the trio, deflects the arrow and sets it aflame)
[*]ability to channel blinding lights in forms of beams / waves (The Two Towers against the Orc army; Return of the King against the Nazghul)
[*]ability to summon lightning at will (used by Gandalf to kill the Balrog, The Two Towers)
[*]very high resistance to actual physical damage, if we consider Gandalfs fall into the depths of Moria.
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Since Sauron is more powerful than either Gandalf and Saruman (by their own admissions respectively), one could also make the guess, that he would be able to reproduce their feats, perhabs on an even greater scale. The rest of the saga (not taken into account here usually) would also point to that idea.
Conclusions
From the presented material, one could probably conclude, that the Jedi would overwhelm Saruman and Sauron in a straight forward melee fight. Yoda appears much faster than either member of the middle-earth team and could probably run circles around either of the two opponents. Kenobi handles his weapon well enough to draw out fights for a very long time, even when facing skilled fighters. Additionally, one should assume that, if a piece of wood is enough to kill Saruman - even if he has some superhuman ability to tank physical damage - a lightsaber would certainly be enough to do the job. The same can be said about Sauron, because a lightsaber is certainly the better weaponary compared to some metal sword. Correct?
Wrong. The crux with the latter point is, that Sauron wasn't defeated with an ordinary blade. The sword (Narsil) that Isildur did utilize there is clearly magical, given that it stays sharp, despite lying around in shreds for more than 3000 years (Boromir cuts himself with the blade in The Fellowship of the ring) and the fact that it is capable to withstand the attacks of ghosts (as seen when Aragorn confronts the King of the Ghost Army in The Return of the King). Thus it is rather questionable if Sauron while wearing the ring can be touched by any ordinary weapon - even if said weapon is a lightsaber. The commentary to the introduction of "FotR" clearly states, that "[...]Victory was near. But the power of the Ring could not be undone."
If that is to be taken as truth, it's rather questionable if Sauron can be defeated at all, unless some magical weapon is used.
Another setup for this fight could result in a totally different outcome: If the opponents decide to exchange first blows over a certain distance, it would seem that the Jedi just have a small chance of overcoming their opposition, because in the "magic and force"-department, Obi-Wan is probably the least capable of all four combatants. And I can't see Yoda removing one of the opponents from the fight with a force push either.
Considering this ideas, I would have to support the idea that Team Middle-Earth might win this little confrontation here, but only barely. That depends upon whether one thinks, that the Jedi can make it into melee range and whether Sauron can be harmed with a "regular" weapon while wearing the One Ring.