I've had this problem with my left crank for a while now. It definitely is to do with cranks not torque'd on properply, grease on taper of spindle/crank, and cheap quality of cranks (for me at least).
I quietened them down a bit by wrapping the spindle with a bit of PTFE tape (for sealing plumbing joins). This reduced the creaking to a tick when I put pressure on it.
All I can think of is just getting a better crankset.
I've had this problem with my left crank for a while now. It definitely is to do with cranks not torque'd on properply, grease on taper of spindle/crank, and cheap quality of cranks (for me at least).
I quietened them down a bit by wrapping the spindle with a bit of PTFE tape (for sealing plumbing joins). This reduced the creaking to a tick when I put pressure on it.
All I can think of is just getting a better crankset.