Bosch are highly regarded and, I think, were actually the people who originally developed this technology? If you go into your local factor you are likely to find NGK have pretty much got the world sewn up for aftermarket plugs and Oxygen sensors (Diesel glow plugs too.) There are other quality makes, Denso comes to mind, and all these names supply original fitment components to manufacturers so quality is "top hole". If you buy from the main dealer you will probably be getting the same part but at a premium price - unless you know someone in the trade who can get discount for you? Pretty much if it's got a plug on it which plugs straight in to the car you're probably on a winner. If you have to start swopping over plugs and soldering wires on then I'd give it a bye.
