I'll second this one. Players should come before companions, but if it's a marginal upgrade for a player and a big upgrade for a companion, I'd give it to the companion.
But seriously...the best part of this entire thing is to talk to everyone prior to the instance. If you disagree with them on looting, don't run with them.
Yes, people are jerks. I rarely ran with people I didn't know because I don't want to have to deal with it.