It depends. What have you been doing before? What are your current levels of strength? What are your goals? Apart from that it is a continuum, if you do SST then HST what will you do after that? SST again? If so, you are doing both SST then HST and HST then SST
That being said, I would HST and then SST. That way you build additional muscle tissue with HST and then you train your body to use this new tissue more efficiently to produce force with SST.
Depends on your goals. HST = grow big; SST = get strong. I'd think HST until you are the size you ultimately want to be, then SST to develop strength within your (then) huge self. That's the Lol way!