From what Kevin related in the video, it would appear that Crows have a relatively easier time becoming breeders because the family structure gives them more options. However, there could be other factors that enter into this for other species of birds. For example, smaller birds may require smaller breeding territories. If they also have lower survival rates, then those who survive may have an easier time breeding. Some species are more "promiscuous" breeders and they may have more opportunities to breed with other birds' mates. In the end, I suppose it depends on what we mean by easier/harder.
I see Crows, Common Grackles, Boat-tailed Grackles, and Red-winged Blackbirds regularly in my yard and when I am in Florida. I recently got a trip to Russia and saw Rooks, Hooded Crows and Eurasian Blackbirds but I am still waiting to see my first Raven. Given my familiarity with these others I am pretty confident that a Raven will stick out from the crowd.