Any conversation about Floyd Mayweather's flaws as a boxer is going to be a short one. A fighter can't go undefeated for over a decade while fighting at the world-championship level if he isn't great.
And, in general, to reach the top of the pound-for-pound rankings requires an extremely well-rounded game. In most cases, you are going to have to do some nitpicking to locate flaws in fighters at that level.
For this list I have relied on The Ring pound-for-pound top 10. I don't entirely agree with their assessments myself, and I think as long as they are owned by a major promoter like Golden Boy, they have to forfeit their traditional nickname of "The Bible of Boxing."
But it's still one of the most recognizable rankings and far more accurate than anything put out by the various alphabet-soup organizations.