The Axis started with grossly incompetent leaders there, with 3rd class troops. The Allies had moderately incompetent leaders. Then there was Rommel, likely the best General of WW2. Facing him was Montgomery, not that good but better than the previous ones.
If I were to qualify the OP question as bitter fighting by both sides on a massive scale; influenced by things like harsh winter conditions, limitations on equipment for the type of fighting that ensued, over-stretched logistics, and a general hatred for one another; it has to be the Battle of Stalingrad. And the kill ratio wasn’t that big.
The campaign perhaps, but I wouldn’t nominate any individual battle.
~Max
The OP stipulates a battle in which neither side committed major errors, though. It was a big blunder for the Germans to have not retreated in Stalingrad and foolishly rely on the Luftwaffe for resupply into the city, a task which the Luftwaffe was not remotely capable of.
Rayks,
I’d go with Isandlwana. It was a clash of two, very different, traditional styles of warfare.
However I’d also list the Battle of Pearl Harbor and the 911 Battle of the WTC as examples of the best planned and best executed attacks of all time.
:dubious: 
God, no.
Stalingrad was a clusterfuck by both sides, primarily because the place was named after Stalin.
The Germans had no specific reason to capture the city, just block the Volga river traffic. Hitler specifically added the city to the list for propaganda reasons.
Similarly, the Russians defended it tooth and nail, specifically because of the same propaganda reasons. Neither side had any real reasons to fight in Stalingrad, and certainly not with that level of intensity.
The only outstanding part of the whole thing was Operation Uranus, where the Soviets encircled the German Sixth Army through a surprise mobile attack.
Velocity,
Oops - thanks!
The question posed by the OP is: “What is the best fought battle of all time?”
I’d say that Pearl Harbor, 9/11 and Isandlwana were perhaps the ‘all time’ best fought. What they have in common is that the attackers: had no supply lines to support; did not take and hold territory and had no follow on strategy. They were isolated battles in which the attackers had total success.
My proposal would be The Battle of Hampton Roads.
The USS Monitor and CSS Virginia meet in open combat in the first battle of ironclad ships. Neither side made any significant errors, the two ships pounded away at each other for most of the day, essentially coming to a draw – though the Monitor did prevent the Virginia from doing further damage to the Union fleet, which can be viewed as a victory.
The British committed several glaring errors there, so it doesnt qualify. The Zulu were nigh perfect, true.
The Monitor didnt use full charges on it’s guns, if it had done so, the Merrimac would have been sunk.
From what I’ve read, the Monitor was using the standard charges of 15 pounds of powder recommended by Dahlgren, the guns’ designer, though it was determined later that they could have used charges up to 30 pounds, which might well have turned the Virginia into swiss cheese. But considering what happened in the Peacemaker accident, it’s understandable that overcharging an iron cannon would be a risk that Dahlgren would be leery of taking.
A good engineer rates his product at considerably less than its ultimate fail point, sometimes 50% less. See: Scottie on Star Trek.
Agincourt was pretty bad, but the absolute worst has to be the Third Battle of the Ypres Salient, aka Passchendaele, during the Great War.
The British shelled impregnable reinforced German trenches for an entire week, which did nothing but turn No Man’s Land into a rained-out mud pit. Then the Tommies reiterated the Gen. Haig Offensive Special, which involved walking blindly into Boche machine gun fire.
In addition to the usual senseless butchery, thousands of British soldiers drowned in the mire.
Replies to the replies regarding Stalingrad: It doesn’t matter how stupid the initial strategy or prescriptive commands were at the start. Von Manstein did order von Paulus to stand. It comes down to the fighting that ensued. A 350,000-strong German force was tasked to take Stalingrad, while a similar soviet force was ordered to defend it. The result: 240,000 Germans killed (counting the 6th Army only) while the 90,000 that surrendered died soon after. The soviets had 600,000 casualties with half them possibly killed. The civilian population of close to a million? I’m assuming most of them managed to flee the Germans. Otherwise, most are likely to have died as only 20,000 civilians were still alive inside the city when it was finally cleared.
I think Clancy was describing the Battle of teh Golan as a whole. The Valley of Tears was the left (northern) Israeli flank, which held; in the right flank, the Syrians broke through, but the remains of the Israeli forces fought a delaying battle and slowed them down enough for reinforcements to arrive.
Incidentally, the first reinforcements to arrive was a brigade of reservists - civilians, three days earlier - in upgraded WW2-era M4 Shermans. They were in such a hurry to get there that they hadn’t had time to fuel up all the tanks, so they had to stop at a civilian gas station at the entrance to the Golan and fill up. The colonel ended up paying for it all with his personal credit card. I don’t know if he was reimbursed.
Melchett: Now, Field Marshal Haig has formulated a brilliant new tactical plan to ensure final victory in the field.
Blackadder: Would this brilliant plan involve us climbing out of our trenches and walking slowly towards the enemy, sir?
Darling: How can you *possibly *know that, Blackadder? It’s classified information !
Blackadder: It’s the same plan that we used last time, and the
seventeen times before that.
Melchett: E-E-Exactly! And that is what so brilliant about it! We
will catch the watchful Hun totally off guard! Doing precisely what we have done eighteen times before is exactly the last thing they’ll expect us to do this time! There is, however, one small problem.
Blackadder: That everyone always gets slaughtered the first ten
seconds.
Melchett: That’s right! And Field Marshal Haig is worried that this
may be depressing the men a tadge.