I like the hollow body can type. Most all of the big turkey call companys put out a owl hooter, I liked H.S. Struts model. I think Primos put out a Hoot Flute which is the same thing, I also have a tried the Power Owl and a similar mouth blown call used same way as a duck call.
A good loud crow call such as the Power Crow seems to work better for me a couple hours after daylight.