Which cement or mortar will give best result when creating low water diversion barriers?
Hydraulic cement sticks to wet fine, but you may need to abrade the surface to get to clean concrete, as it won't like a greasy, dirty or otherwise befouled surface. 

However, what I would actually do (and have actually done) to direct water on a concrete floor is to use a diamond saw to cut a small channel into the surface - much neater and tidier - also easier to walk or roll over. And much less wet area.