Hoping to start a debate, and this kind of topic always seems to work!
So my contention is, British aircraft post-WW2 have generally been better than their US peers.
Well, until the Government cut all funding*, British aircraft were collecting many records - for example the Fairey Delta 2 brole the existing record by over 300mph, the largest increase until the Blackbird, and was the first to go over 1,000mph
The world's first jet airliner was British, and a modified version is still in service with the RAF
The world's first (and for a long while only) properly successful VTOL aircraft was British
Both nations developed an interceptor in 1954, that first flew in 1958. One of them was stuffed with high-tech concepts to improve performance. The other performed better
Where roughly equivalent aircraft of both sides met in warfare (Indo-Pakistani wars, for example) British aircraft tended to come out on top. However, I'll admit this is a rare occurance and may be down to factors beyond the aircraft themselves.
I'll stop there, as I'm sure I have provided enough appetizers for a lengthy chew
* A lement you may hear often in this topic