Refractors are mainly used for imaging these days. A good refractor makes a fine deep sky scope, with no central obstruction you can get really nice contrast in your views. However most visual observers still prefer the aperture that a big dob can provide. It is simply bang for buck!
Obsessions web site has a comparison of an 8" to their bigger scopes starting at 12.5" here
http://www.obsessiontelescopes.com/index.php I am sure there are other sites but no aware of them.
Malcolm