I get a pretty good bang for the buck with the mash hop. It seems to add a smooth hoppy flavor without really adding any more hops.
I also use aroma hops for the appropriate styles, but I can perceive a difference with the first wort hops -- I've brewed the same recipe with and without and the second batch was much smoother and a bit hoppier.
Of course there are many other things it could be, but if it works why not?
Cheers!
Brad