It's almost impossible to give a strict hierarchy because the curve of performance gains for the various aero improvements are not the same. Some are very steep at the bottom end but flatten considerably at the top, and the differences between "pretty good" and "great" are very small. Others are closer to linear, where every step up the ladder in quality gives a similar performance gain. So the answer to the question depends somewhat on where you start.
I like to fiddle with the Aeroweenie Aero Assistant. It's not the "definitive" model for aero improvements, but it seems to be a well-reasoned one. One thing that stands out to me is how much difference they say there is between a premium aerobar set up and a middle tier one compared how little the difference they say there is between a middle tier, upper-middle tier, and high end frame. Another is how overvalued high end wheels are in their estimation. Their model suggests a set of high end, deep-aero front/rear disc wheels is worth only 17 seconds on a 40k over a 30mm semi-aero alloy wheels with a ~$100 Wheel Builders cover for the rear.
"They're made of latex, not nitroglycerin"
I like to fiddle with the Aeroweenie Aero Assistant. It's not the "definitive" model for aero improvements, but it seems to be a well-reasoned one. One thing that stands out to me is how much difference they say there is between a premium aerobar set up and a middle tier one compared how little the difference they say there is between a middle tier, upper-middle tier, and high end frame. Another is how overvalued high end wheels are in their estimation. Their model suggests a set of high end, deep-aero front/rear disc wheels is worth only 17 seconds on a 40k over a 30mm semi-aero alloy wheels with a ~$100 Wheel Builders cover for the rear.
"They're made of latex, not nitroglycerin"