LHR ATC is great.
FRA also does a nice job.
The U.S. controllers should give the foreign carriers a little break. I hear them rattle off clearances to foreign carriers and it's too much info for a non-native speaker.
And some of the foreign carriers need to up their standards in the U.S. It's more crowded and faster paced. Nothing like having a visual to LAX 24R overshoot the entire airport while turning from downwind/base. We deviated 1.5 nm left of 25L centerline, leveled off, and watched the 747 slide by 1300'(1700'?...report had the exact distance) laterally at our 2 o'clock position. Passengers on the right side of the a/c during deplaning - "that guy on the right looked really close." "Oh, he didn't look really close, he WAS really close."
Fly up the East Coast of the U.S., Washington Center in NYC, on a weather day. Probably the busiest air corridor in the world. Seven major airports - IAD, DCA, BWI, PHL, EWR, LGA and JFK, all in about 200 nm.
And that's not counting the over flight traffic heading towards BOS, or coming NE from CLT or ATL, of MEM/DFW NE towards Europe.
Sorry, but nothing overseas compares to the demands of the U.S. ATC system. I wonder why it's not less RT intensive but it is what it is.