Cinematik.net is an amazing private Film tracker. It boasts a strong community of film lovers and an even stronger database of torrents. The community has strict rules as to what films can be uploaded, and strongly urges the use of .img, .iso, or VIDEO_TS format with uploads of DivX and Xvid only being allowed as a last resort if a DVD of a film doesn't exist!
While the rules seem strict, this tracker has an amazingly laid back appeal, especially with the frequented Forums, Movie of the Week, and their Gold and Silver torrents (read below for info) specials every month!
Even though I have no experience with Karagarga, which gets toted as one of the best and most extensive private film trackers on the internet, I insist that Cinematik.net gives it a serious run for its money. Also, its probably easier to keep a good ratio at Cinematik.net!