Bottom line: you can't go wrong with NGK. Can't really go wrong with OEM Bosch either but I'd just stick with NGK and make sure you gap them right, call it a day. I'd avoid Denso.
Change the spark plugs too while you are at it, with NGK BKR6EIX plugs (or BKR6E if you want to save money but these are the copper plugs and will not last as long as the iridium BKR6EIX).
changed out some spark plugs, shop here: http://autotech.com/passat/b6-3-6l-2006-2009/3-6l-vr6-ngk-spark-plug.html also I decided to get a new valve cover (comes with new gasket, bolts, bolt o-rings, and of course a new PCV oil separator that are prone to fail)
OEM plugs are good but NGK iridiums are just as good and cheaper. If your car is stock, which if memory served correctly it is, then use NGK BKR8EIX.
So here is my experience with gaps on this engine. The wife 09 Passat was misfiring so I decide to replace the plugs. I buy Autolite double platinums which were gapped huge. Turns out the 0.032 gap was not correct after all and it should have been 0.028. Big difference, this baby flies again (GIAC tune).
I changed the spark plugs to Autolite Double Plat plugs from Autozone. The smoke cleared up and it is MUCH easier to keep cranked in the cold (30's F) in the morning. It still has a very light stumble every few cycles and a louder engine idle than I'd like, but runs good and seems to be much better.
I had NGK PFR6Q and it ran fine. But... now I use the stock NGK plugs
NGK BKR7EIX is a popular plug for 1.8T and 2.0T, but it is one step colder in the heat range. Fine for those whom don't see freezing and below temps.
All the recommended denso plugs have the wrong gap. They list 1.1mm gap for the 2.0t The recommended gap should be .7 to .8 mm Plus the "20" heat range misfired a lot in the cold for me (about 20 deg F)
The NGK's listed have a colder heat range. Great in the summer, it will misfire like crazy in the winter
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