Once we have asserted that Luffy >> Kidd
Then the rest comes swiftly
We have the author portraying Zoro and Luffy clash on equal ground back at Whisky Peak. Then what happens? A few arcs pass and Luffy unlocks the gears which make him defeat Lucci, too bad in an extreme difficulty fight. Zoro on the other hand is capable to completely dissipate Kaku thanks to his Asura, and no solds his best attack in the blink of an eye.
Silver Mist was legit more intimidating than G3 at the time, mostly due the speed difference. G3 was slow as hell albeit possibly even more powerful.
The two of them undertake similar trainings I would say. Luffy is more disciplined haki wise, but Zoro undertakes the hardest survival training on the other hand.
Zoro and Luffy are equally potent Post TS.
Luffy becomes stronger than Zoro in WCI and much stronger in Udon, but Zoro undertakes the Enma training to attempt to catch up once again and I seriously feel he did by learning advanced CoA in return, or else what was the point of this in the first place.
This is my speculation, however calculated one, based off manga notions.