For what it's worth, I put a Duralast platinum AGM battery in my 09 tdi jsw 7 years ago, and it's been working flawlessly ever since. Maybe the '09 isn't sensitive to the battery type like newer models, but in any case I haven't had any problems and my car always starts immediately, and it gets really cold where I live. So I can't comment on their suitability in all VWs, as a apparently it's complicated, but the Autozone AGM battery will last a long time, in my experience. Worth every penny.
I've had a lot of different brands of battery over the years, but the AutoZone duralasts have consistently been the best. I can't remember which manufacturer makes them (Johnson maybe?), but at this point, I'm a fan. I have two Duralast Golds in an 07 Duramax, and they're going on 10 years now, and that truck sits A LOT. Sometimes I get a charger on it, but not very often, and they're still doing fine. Amazing.