I've gone back and forth on Netflix over the past couple of years because of their "service splitting" deal (though I guess I should have bought stock back when I was complaining about them).
I currently do both DVD and streaming on Netflix, because I just can't find everything on one or the other. Streaming seems to be good for some newer movies, but others you can only get on DVD, at least for some months after their release. DVD is better for older classic movies. As mentioned, streaming seems to have a lot of TV. I just a couple of months ago finished doing the DVD mail game with all the seasons of "Chuck", and two weeks after I finished, it moved to streaming.
Also as AJ mentioned, you won't find everything on one service. I have Amazon as well, including a bunch of free stuff with my Prime membership. Sometimes I end up paying for a streaming new release movie on Amazon that I could get for free (i.e., included in my monthly fee) on the DVD side of Netflix, except it has "very long wait" next to it in my DVD queue, and I don't want to wait a very long time.
If I could get everything I wanted via streaming, that would generally be my primary choice. In fact when I buy stuff nowadays that I really like, I buy it as Amazon streaming versus DVD.