My biggest issues have been at LAX, T5 (where AA used to arrive). I have never been grilled harder by the customs agents than there, other than at MEM! Otherwise, MIA, ORD, and even LAX TBIT have all been relatively easy - few if no questions.

I've still never been pulled into secondary to have my luggage inspected (coming into the US), but the grilling I get when coming back into my own country really sucks.