I've used NGK's for most of my mechanical life.
I do have to point out, in defense of the platinum +4 series plugs, that while they do "shroud" the spark a bit, they're also designed for use in higher compression engines, which may quench the spark due to the resistance created in the atmosphere of the combustion chamber.
For OEM cars, they solve a problem that doesn't exist to begin with, when dealing with "new" conventional spark plug technology. In that sense, their feasibility is destroyed, making them essentially a gimmick, of sorts.
In defense of Bosch in general, they do make several other products that I choose over others... just not spark plugs.
