HackingNetflix highlights a survey by TechBargains of what streaming services do most cord cutters use. As you can see, they must have allowed people to enter more than one service, but the clear winners are Netflix and Youtube.
Obviously YouTube has the advantage of being free, so I'm surprised that isn't closer to 100 percent, but then Netflix is built into almost every TV and DVD player sold these days.
The one thing I think is not mentioned enough in the media is the free movies and TV available to Amazon Prime members. A combination of the free Prime Video and the paid Amazon streaming could be a fairly compelling streaming solution.
I have noticed more free streaming options on iTunes, including the season premiere or pilot of a few TV shows.