I take a middle road, and if you read between the lines of some of the more learned opinions here, they seem to lean that way too.
In my opinion (that is the term most recommendations here should start with, however, much more commonly I see "without a doubt") it is indeed size that matters. Amps need fast access to power for dynamics. Don't throttle the power with a light cord.
I use generic 10 awg power cords. I do take the ends off of them and verify they have been well terminated. If you don't feel comfortable with doing that and want something absolutely reliable, then spend 10x as much and get a $500 power cord. Make sure it is heavy gauge, at least 12 awg, preferably 10. I recently bought an amp with a 2 year wait list. I was very lucky to buy it before someone else did. the seller included the upgraded power cord he had purchased. It was a $300 cord. I looked it up and it was 17 awg. I feel certain the cord is why he was unhappy with the amp. I used it on my CD transport.
Like others here say, cords are not tone control. Once you get plenty of power to your amp, anything else you hear is likely affirmation bias.
Jerry