Standing right next to you on this one. I, too, have used both products, and my favorite by far is the Niagra non-aerosol. I think it smells better, too. I can purchase the Niagra at my local grocery store right down the street - not true of the Best Press, which is only available at the quilt shop.
I think I paid $2.99 on sale for my 22 oz Niagra.
p.s. I use my emptied Best Press spray bottle for plain water.