On the whole, almost all of my passes through CBP have been like passing through immigration/customs at SIN, NRT, MAD etc.

The worst I've had was at BOS (agents working primary line made me go to secondary when I couldn't locate the invite to my friends wedding. Secondary wasn't impressed that the agents upstairs were wasting their time) and once at JFK (agent refused to believe that I could afford my own holiday). Passes through LAX, SFO and Blaine have been average at worst. DFW was the best to date.

TSA on the other hand...
The last time I've had a "good" passage through TSA was before the body scanners and liquid bans.