Hi mmarsh. I felt compelled to respond to your post, nothing personal.
Remember it was the BOB that cost the Luftwaffe their best pilots. And most of the fighter aces were shot down by Allied Planes not Soviet. The allies had more planes and better quality too. The Me-109G (the most common German fighter) was inferior to almost every allied plane. The Thunderbolts, Spitfires IX, + XIII and Mustangs ate it for breakfast.
It's simply untrue that the Battle of Britain cost the Luftwaffe their best pilots and also untrue that most of the fighter aces were downed against allied aircraft. Erich Hartmann, the leading German ace of the war (and the highest scoring fighter ace in history) was never shot down and spent the vast majority of his time on the Eastern Front, under JG52. He did not even complete his fighter pilot training until 1942 so to say that most of the fighter aces were shot down against the RAF is sadly, untrue.
Hans Ulrich Rudel, although a Stuka pilot, again was not downed by the RAF. Rudel was the highest decorated German individual in WW2 and claimed over 2000 kills. I think it's safe to say that the Luftwaffe lost some good pilots in the Battle of Britain but to say that they lost their best pilots is a falsehood.
Better planes? Again I'm not so sure. The Focke-Wulf Fw 190 was superior to the Spitfire MKV when it was launched in 1941. German fighter design would eventually lead to the ME 262; had this plane been available in decent numbers it would have caused the Allies nothing short of a nightmare. Even historically they inflicted a 4-1 kill ratio on Allied bombers and fighter escorts.
The main problem for the Luftwaffe was 1) lack of trained pilots and 2) lack of fuel. Neither of these points would have anything like the impact they had historically without the presence of an Eastern Front.
The Luftwaffe had 2 exceptional fighter groups JG 26 and JG 52. Both the USAF and RAF had dozens of "good" squadrons such as the 352nd and 354th FG. In both the ETO and PTO, the few exceptional Axis squadrons eventually lost out to the endless supply of qualified Allied pilots. Therefore I would think that the allies would have air superiority.
You are assuming that a 'fortress Britain' would still have been built up had there been no Eastern Front. This is a rather optimistic assumption given that Europe (USSR aside) would be under the domination of Germany, with their full combat strength available to apply against the Western Allies. Politically, it's an absolute non-starter in my eyes; I can't envisage the US being prepared to fortify the UK under those circumstances. Just say for argument's sake that it did happen then the Allies might generally have had local air superiority but they would have nothing like the air supremacy they enjoyed in reality.
The allies had fantastic Fighter-Bombers, Overlord proved that Germany couldn't move its tanks during the day because of them. Furthermore the best German Tanks were built in response to Russian Armor, if they never faced the T-34 then they never would have invented the various heavy armor vehicles (Tiger, panther, jadspanther) that they did. Therefore the Allies would have only faced Panzer III and IV which the Shermans could face on equal terms. And again, given the numerical superiority of allied Tanks, advantage allies.
My comments above partly dismiss this. The Allies would not enjoy the air supremacy they had in actuality. It's also untrue that the best German tanks were built in response to the T-34; only the Panther was as a direct result as the Tiger was already in the advanced planning stage in 1941. though admittedly the T-34 did cause some requirements to be changed. Moreover, it is likely that the Germans would have found out about the T-34 at some point so designs such as the Panther would have followed eventually. Finally you are forgetting about the famous '88 AA gun, that the Germans put to great use as an AT gun. The '88 would take care of any allied tank short of the M26 Pershing and would be highly effective for a defensive German Army.
The allied armoured divisions would not be facing just Panzer IIIs and IVs but also at least Tiger Is and '88 AT guns, a vastly different scenario.
Of course the Germany Army would have been under the continually bombardment of the Allied Fleet.
Only if they were stupid enough to place their divisions in range, which I doubt they would be.
Lastly the allies had better infantry, they were less experianced but they were better equipped and better supported with artillery and heavy weapons. Remember the German Army was outnumbered by the American Army Alone, excluding the other Allies.
It's highly debatable that the Allies had better infantry - why do you say this? One of the things to consider is that the US Army, in their Air/Land Battle 2000 concept devised in the 1980s, recommended adopting the mission style tactics used by the Wehrmacht in WW2. I think that speaks volumes on the impact that the German Army, made up largely of infantry divisions, had on US commanders during WW2. The Allies had some excellent infantry but to say that they were better than Germany infantry... All I can say is that you'd be in the minority with that opinion.
Overlord would have been more costly for the allies, perhaps in the 10s of Thousands KIA, but I think the result would have been the same.
IMO the results would have been far different. The only way to ensure Allied victory in Europe had an Eastern Front not taken place would bring a terrible price.
Anthrax contamination of Germany or the dropping of nuclear weapons on Germany. Take your pick.