I believe the 9s. You have no pair, but 6 groups already 234(m) 67(m) 34(p) 79(p) 678(s) 89(s). If you discard the 9s, then you can accept a 5s or another 8s leaving you the two 8s as your pair. 79p is more likely to promote into a full group than 89s because 89s only accepts the 7s, but 79p accepts the 6p or the 8p to become better. If we draw the 6p we will discard the 9p and have possible pinfu.