I take tech marines with Grey Knights. He has ward staff, rad and psy grenades and 3 skulls to screw hound rush.
The priest and inquisitor options help you get more rad and psy grenades on the table. His plasma and powerfist attacks are nice add ons.
However with strike marines this alows for a cheap unit to do well and have two 2+ invulnerable saving characters in a squad. Heck you can have 6 possible.
My fav is tech marine with 6 crusaders and 4 deathcult.
I think dreadnoughts aren't bad. At least the venerable in dark angels have been updated for 6th and I seen them due pretty well.
Besides rifle dreads deep striking melta/ heavy flamer drop pod dreads are a pain. I fear these a bit more than the rifle dread.
My opinion is that dreads are supposed to ge a match to MCs. Thanks to MC's Smash attacks it's not a fair fight. A ivulnerable save akin to terminator makes sense to me.