Which harsh Metal vocalist is the most easy to understand?

Personally I can understand most if not all of the lyrics from Chuck
Shulinder of Death and Burton C, Bell of Fear Factory

BQ- Top ten harsh Metal vocalists?
BQ2- Top ten clean vocalists?
BQ3- What vocals do you prefer, harsh or clean? Both?
BQ4- Do you really care if you can't understand the lyrics? I listen
to both X Japan and Dir En Grey which is in Japanese and it's great.