I'm new to Delta Green but I am enjoying it immensly. The thing that I like about Delta Green is that it provides reasons for people to investigate the mythos. In Call of Cthulhu you might have run a scenario where the head of one of your ghost hunters gets chopped off. Any normal person is going run away screaming at that point, but Delta Green has a reason and rational to be there. Also using the example of the ghost hunters who are you going to recruit, now that curious Johnny had his head cut off? Delta Green provides you with a never ending supply of agents and friendlies to pull from. Personally I am liking Delta Green better than Call of Cthulhu and I LOVE Call of Cthulhu!