Al Natura is my favourite biomarkt in Bonn as it offers a great range of bio and vegan products, all at relatively cheap prices. Their own 'al natura' brand provides top quality products and is usually the cheapest in their range (you can also get many of these products at DM). Overall I find it a bit cheaper than Denns and Basic, although they have a slightly smaller range. Would be great if they started adding a vegan symbol to their price labels as well.
Cons: Vegan labelling would be great