I think a lot of it is Jams keeps his material at a monthly at best level while Doug is weekly. It keeps things from getting tired and overdone.
The nature of the material probably also helps. James can and does (mostly) limit what he covers to "just the mockable" parts while Doug is stuck with the full movie. When you have to cover everything, not every joke will land, and the efforts can come off pretentious or unfair (ie: plot holes in movies for 5 year olds).
Probably a stupid question but isnt Cinemassacre more independent and DIY than Channel awesome?
Channel Awesome guys use more CG and budget for the studio. James actually probably spends less because his venue is obvious. But that insane xmas episode seemed to be an independent room.
As for James' best DIY work, it was his black and white and red zombie flick. The graveyard depicted in the movie was in his basement, which is insane