"I'm willing to bet the US infantry were the hardest opponents for the Germans to fight as far as squad level fighting went."
Only in terms of firepower distribution I would think. The US infantry squad had a much more evenly balanced firepower distribution than the British. The British Bren was slightly better for sustained fire than the BAR because of it's thirty round magazines and quick change barrel, but the firepower advantage of the M1 rifle over the bolt action SMLE really gives the overall squad firepower advantage to the US.
I think the German squad organization and tactics were the best overall but their effectiveness would only have increased exponentially if the war had continued and they had been able to largely replace the Mauser Kar 98K rifle with the MP-44 assault rifle.