It all depends on your preference; I prefer the bridle path short...so I use a 15 blade. In the winter, I use a 7 blade, though, to prevent the cold from irritating the area from it being too short.
If you don't show, it doesn't matter if it's 'smooth' so you could use shears over it; just becareful, as you could snip yourself or your horse if the horse jerks, or shakes his head at the wrong time!!! Well...atleast the shears I use will do damage quickly...as they are super sharp for dog grooming, hahaha.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."