North America is a rather large continent and like, say, Europe, standards will vary over such a large area.
The New York accent may sound pushy or even aggressive, but then so do certain Eastern European ones and even the occasional Scottish accent.
Some parts of the US use local slang but that is hardly as bad as, say, the Spanish or French languages frequently used, which blatantly ignores ICAO and seriously reduces the situational awareness of other crews. Irish ATC tends to be clear and cautious, but the local procedures are often eccentric and unpredictable and they almost never give EATs or accurate track miles when asked. Italy is a law unto itself but even there ATC often varies from North to South.
The Swiss and parts of Germany like to try to climb aircraft at minimum rates of climb at high altitude, obviously without understanding the physics but they don't get upset when one says one is 'unable'. The Swiss also like to keep aircraft high with tailwinds on approach but then they have the excuse of terrain issues.
All of these are easily managed, usually, but are undesirable.
The issue I would have with, in particular, some ATC centres in the States, is the apparently envelope-pushing clearances some of them issue. I won't name airfields but for example the various speed, track miles, frequent late approach/runway changes that can be given are a more serious problem. This problem grows with the weight of the type and the length of the flights.
All that said, I do enjoy flying in the States and my positive experiences far, far outweigh negative ones there.
I do take issue with the following though:
Also, with my experience in international flying, which is considerable, the US still has the best ATC system and controllers. With London ATC a very close second.
London is well ahead of the rest.
If only they could get their ATC people to run their airport security!