FBKampfer
Banned
Not really in terms of aircraft design, both the Brits and US kept up with that and surpassed them in engine technology. There were some edges in aircraft armament, but not enough to be called 'world leaders'. Jet engine design wasn't world beating either, they just went for a lower quality engine to maximize the result given the material and time constraints, so got into service first, but weren't the 'best' really. In terms of aerodynamics certainly the Me262 was well designed, but again not world beating. In terms of night fighting equipment again they weren't the only ones with achievements in that direction, they just rushed theirs into service out of desperation. For helicopters Sikorsky was probably the best in the world:
https://en.wikipedia.org/wiki/Sikorsky_R-4
Guided munitions the Germans were first in, but hardly the only ones:
https://en.wikipedia.org/wiki/ASM-N-2_Bat
The Germans weren't anything particularly special in terms of torpedo design either. In terms of tank guns yes the Germans probably had the best pound for pound cannons, but that doesn't mean much when the enemy has air superiority. The Allies had better AAA and radar. In terms of small arms it was generally a wash but for the MG42 and StG 44, but were behind in semi-auto battle rifles. Yes the Panzerfaust was probably the best in the war, but the Super Bazooka, which just missed service, was the best rocket launcher of the war. I'll give you submarine design, but then no one else really needed to perfect that but for Germany, as they were all well ahead in surface ship design.
So in general the Germans weren't really that far ahead in the areas they were ahead in with the exception of rocketry and a few other areas and were behind in a bunch of other areas.
Perhaps not in active-service piston engine fighters, but particularly in second generation jet aircraft, and advanced research projects. The difference was that Germany tended to push these into production as opposed to toying with them for another five years.
And the German engines might not have been better as produced, but were better as designed. Axial compressors scale much better than centrifugal compressors, and if you want to move forward, you'll need to scale those suckers up.
And the Fa 223 was arguably the best design for a military helicopter.
And German guided munitions weren't merely limited to gravity bombs either, but included MCLOS A2A missiles, MCLOS A2G missiles, MCLOS bombs, ATM's and conceptual SACLOS beam-riding and SARH SAM's.
It should also noted that ASM-N2 was only successful because the Japanese lacked any ability to counter even the primitive radar guidance possible in the 1940's. It's possible that they were not even aware of how the device functioned, in contrast with the German MCLOS weapons, who's operating principal was relatively easy to discern, and the intended primary target of ships, who would always be capable of jamming if they carried radio. The real trick they missed was using them against land targets.
Germany could hold air-parity in 1941, the POD. And this might butterfly away the P-51 and F4U on top of allowing Germany free reign over Europe. Which means Germany's excellent cannons (coupled with their integrated mils-radian optical sights, giving up to 85% first-round-hit probability at 2000m) are very much in play.
The Allies had better radar, and had went ahead with development radar-fusing, whereas Germany back-burnered most of those projects in early 1940.
The Germans also had the G43, but again ran into the constraints of wartime production, which they likely would not ITTL. And with the Mp 44, and later Stg 45(M), the granddaddy of the G3 and G36, and without literally the largest conflict in human history to distract them, I think they're going to be able to update their standard infantry weapons.
And Germany also had the PAW 600
Realistically, the Allies led in radar and electronics, strategic bomber, and large surface ship design.
And besides, a lead is still a lead. The point is that it would be temporary.