Question when crossing the border via non-Nexus lane

So, my wife and I have Nexus cards, so when we cross the border we always used Nexus lane with no problem. This time, we are traveling with my brother in law who is a Korean citizen (hence no Nexus holder). Definitely we will NOT use Nexus lane. My question is - if we use a regular lane, should we show the border officer our Nexus cards or passport while my brother in law show his passport.

Also, are the officers on regular lanes usually picker than those on Nexus lanes? or maybe it doesn't matter? I expect it will def take longer to pass the border via non-nexus lane..