There is simply no such thing as the best way to grip a mouse. Everyone has their own answer to the question, and that answer will be whatever grip style they find most comfortable. Shroud has insane aim not because he uses claw grip, but because he’s been clicking on heads full-time since 2014!
Once again, there is nothing wrong with experimenting with different grip styles, especially if you’re pursuing perfect aim. That being said, switching to a less comfortable grip style is not the way to go!