Between PicoSure or PicoWay Resolve, what is the best to heal my burn scar? (Photo)

I have this scar more than 20 years. I have done a lot of laser including 4 frexel and 8 times Qswitch laser but its still not fade as much as i want. Now i have picosure laser and about to have a 2 session very soon but i have read that picoway is better in terms of pulse duration and energy to remove pigmentation. Which one is actually better for remove my scar and how many session do i need?