Agree with other posters.
Faster charging means not much especially if you have a smart alternator.
I found the VW 2L TDI extremely tolerant as for starter battery, more than any other van, even ones with smaller 1600 engines. Mine starts happily after 2 weeks of sleep under 0 C' on the original tiny 70 Ah EFB, 3 winters old.
I would go for any good brand AGM or EFB one, with high max current, capacity 80 to 90 Ah seems the good compromise between capacity and size/easy to install.
As an example here in.my place is difficult to beat price/performance an Exide EFB (similar to my OEM one) or, if you want to spend a little more a Varta Silver/AGM. Many Bosch are just Varta rebranded, just at higher price (unverified urban legend).