depending on the area you are training in. mobs die in 1 hit pinaka> 2 hit skii, mobs die in 1 hit skii > 1 hit pinaka
as i know ..here is 12-13atk lack between them 120ski about 133slow spear.. but some guide tested said...if all buff..152spear will better than ski.
This is my take on it. Unless you have money to "blow" I would highly recommend Sky Skies since they are much faster and kills mobs faster. Although they get very expensive from 122 wa and up. It can cost you as little as 4b just for 122 wa skies. While on the other hand, Pinaka or any other slow spear provides you with high damage in a slower pace for a cheaper price. So It depends on whether you wanna do high damage in a much slower pace or whether you wanna kill mobs faster with less damage..