It depends somewhat on the requirements of this part. First, there is no draft defined anywhere on the part so if "zero draft" is a requirement, then the tooling and subsequent parting lines be probably very tricky, e.g. multiple slides to form the knob bumps.
Will the final production knob be textured? The depth and type of texture will push you towards larger draft angles.
Assuming a flat parting line (simple) tool is the goal, I'd probably part it somewhere near one side or the other of the knob bumps, as shown in the picture, and draft all the surfaces away from the parting line, keeping the production part texture in mind (deeper texture needs more draft) before adding the fillets and rounds that make the knob bumps smooth.