I find that the true "10x" engineers are staff-level engineers that a) have strong technical ability and b) are really good at communicating and mentoring. They are 10x because they are able to make all of the "normal" engineers around them better and thus level up the productivity of the entire team. Engineers like this are worth their weight in gold and far more valuable than the infamous "brilliant jerks" who can easily design an excessively complex system by themselves that magically only they are able to maintain effectively.
