No one knows the sweet spot, we only know it is somewhere in that range. Exactly where depends on your arm, your VTA and most of all you. Only you can decide these things, and only by listening.
Start by setting VTF right smack in the middle, and then getting VTA dialed in. Then tweak VTF up very slightly up or down and see which one you prefer. If you have no strong preference (very likely, but you never know) then leave well enough be and focus on fine tuning VTA.
Remember, VTF changes downward pressure on the stylus which will have a small effect on the cantilever angle, which affects SRA. So no point getting real precise with VTA until you are happy with VTF, as it may change leaving you to do it all over again.