Murilo would have done the best IMO, followed by Royce then Royler. From what I've heard though Royler has the best BJJ skills (or is the best teacher anyways). Regardless though, Royce was chosen because if he lost they would have stronger, better Gracies to come in... guess he proved that it wasn't necessary though, which is one of the reason's Royce is the man. There was only 3 people to really look out for at UFC 1 for Royce, Pat Smith, Gerard Gourdeau and obviously Ken Shamrock (who was slated against Pat oddly ('
'), and with none of these guys knowing how to defend against a grappler using a gi, they would have all most likely won.
Was Busta even affiliated with the Gracie family back in '93?
EDIT: I misread your post and thought Renzo was Royce... just woke up. So my order is: