User blog comment:Xouzoura/What colour of haki do you think Luffy will decide to improve the most ?/@comment-67.230.74.230-20100829223714

more than likely the colour of observation since he used it against Dracule Mihawk at the fight at marine ford and then his primary one would be the colour of the Conquering King (Haōshoku Haki) since thats the one he has the greatest affinity for