Both are excellent.

Cohen is less about psychological techniques & more about setting goals, gaining agreement while not being invested to the point of life & death. Caring about the outcome but you won’t blow your head off if it doesn’t work out. Softer approach in a way if that makes sense.

Voss is deep into unbelievable psychological analysis on mirroring techniques, empathy etc & due to the nature of his work; it typically was life/death type stuff. Harder approach.

Ironically, The net net of anything is that you have to be genuine & be yourself. I’ve done software sales for 25+ years & the ones that are the best (long term) are extremely smart & very genuine to themselves whether that be a softer approach or hard ass dickhead :). You are who you are. Be that.