You admitted that "illegal" is a dehumanizing term at the start of this conversation. Anyway, my position is the same as Ferguson and emailking. "Illegal immigrant" is fine. "Illegal" as a noun is generally speaking a racially motivated pejorative.
That's the thing, I
don't personally find it dehumanizing. It's accurate. My point is even if it were dehumanizing in the way you say, it's not the same as a racial slur. People made the choice to break the rules, cut in front of the immigrants coming here properly, and then act all entitled and offended when called what they are. No one chooses their race. You are letting the conservatives define the terms.