Man we love talking about the validity Squat variations.... could be worse we could love to talk about how to better Isolate the pectorals.
I love all the squats and do them all sometimes even in the same work out. I am so gratefully I learned ho to properly perform the high bar Back squat as it has enabled me to apply the FS and OHS more appropriately. The only thing is I like the narrow stance so much I now do my LBBS with a similar foot positioning which I know is a no no as far as al you PLing buffs go. I think I just have a narrow pelvis and it knda hurts to have my feet to wide.
As far as gaining mass I have to say a mixture of HBBS LBBS and FS would probably be my bet as they all allow for different muscle recruitment and loading capabilities. Now if we bring in the DL it cloud shift around the importance a little but in my opinion at least one of the BS variations mould be important as a catalyst for synergistic muscle coupling and balance between the front and backside mechanics in a integrated lift having an eccentric to concentric phase progression of contraction.