Board Thread:Questions and Answers/@comment-203.81.212.210-20150124161407/@comment-68.226.81.85-20150125011345

It's a good idea to eventually upgrade all of them for maximum benefit, but it's a good start increasing the ones with the lower percentages first.

Prophet Cookie's Majestic Beard would be a good place to start but it's a S rank treasure so it's your call.