I would concur with others - more important is how many other flights are arriving at the same terminal.

My experience of JFK is that I am through in about 10 minutes. This is taking the 1st flight out though, which lands about 11:30 local time. Flying J you get out and to the head of the queue and are through PDQ.

With people flying at the back next to the rear gunner it could easily take over an hour to get past immigration.

I didn't find the snapshot/fingerprint malarky made much difference to the overall time taken.

I can't comment so much on EWR as I last flew there in 1999. For what it's worth I found that painless too.