I saw Len Cariou in the original production, George Hearn on tour with Sweeney (w/ Angela) at the Kennedy Center, and saw the Brian Stokes Mitchell / Christine Baranski Sweeney at last year's Sondheim festival.
I enjoyed all three actors. Cariou was the most intense in the role - his Ephiphany had the audience squirming in their seats. Hearn found more humor in the character, which I think worked to the tour's advantage (the subject matter of Sweeney is, after all, pretty grim stuff)- A Little Priest was a highlight, I thought, in his performance. Stokes managed to chart a course in the role that wasn't always predictable... shifting the character between madness and matter-of-factness. And of course with a fabulous voice to bring those great songs to life.
Ray is the author of the Brad Frame mystery series, and two suspense novels. He is also the author of a one man play based on Ben Franklin. http://www.rayflynt.com