I've spent years traveling the world. Many years recently entering the US. I find US immigration SO SO SO much nicer than than the British. And that's coming from a Brit!
Unless you enter Miami where they are utter cunts.
DH is a US citizen and is shocked at how nasty the UK are to him and my ds. It's upsets me every time.
I find the US border patrol so nice and courteous, I'm embarrassed whenever we enter Britain.