Best forks for a 150sx?

I am on the hunt for a 150sx. I have read the that the WP4cs forks on the older models cost a lot to get right and the new aer forks are not appealing to me. My question is what would be the best spring fork to drop in any year 150sx or is the switch to air is really worth it? If there is a better fork for this bike out there would you recommend dropping it in the old or newer gen as well? lower B rider and 165lbs if it helps