Easily a bad ref. A bad decision doesn't change what happened in the ring. Bad judges could have given Guerrero a UD over Floyd. Doesn't change the fact that Floyd schooled him and everyone that watched knows it. A bad ref can actually alter the flow of the fight and/or force terrible stoppages (too early OR too late), which can directly and tangibly affect the fighters. Bad judges are just people giving bad/corrupt opinions on a fight.
Bad ref. Bad judging doesn't put a boxer's health at risk. Bad officiating is certainly capable of doing so.
I wouldn't put one over the other, they are both equally as bad. A bad ref can cause a fighter to take too much damage but that fighters corner can always step in. Bad decisions by judges can at times make or break a fighter. It's a lose, lose situation.