I recall this being discussed somewhere in the past but..
If we go into this Mikael of Opeth versus Mikael of DT, which is anyway kind of stupid, I´d say Mikael wins.
I have to say, I don´t see the reason why Åkerfeldt is considered the best growler by so many people, when his voice is so mediocre. He differs from an ordinary bloond-squirting gutbreaker from Belgium with the money spent on recording his vocals and "angelic" clean voice, which is like´s Jonas Renkse reduced with 4. I know, I´ve never heard him singing out of tune, but well - I never heard him doing stuff which would ask for more than five notes, either.
Mikeal S on the other, has also his cons. His growling has stuck on the same thing since Haven, becoming more monotonic and so on. On The Gallery he sang with passion, but it´s just that badly arranged tired coughing (the newest album, mostly).
To avoid making the dude cry, and for the record, his clean voice on the other hand, has taken a long jump from boyish and neo-power metal Skydancer-times to this melodramatic singer that he now is. He distantly reminds me of these highly appreciated female pop-singers, who a sing a ballad a nighte in the radio channels aimed for the people over 32.
Anyway, If you want a mix between cleans and distortion, I´d say try Vintersorg. He´s good.