Have not found any stronger ARBs. I am using B6 with OEM Ti springs. On 17" wheels the compromise between sporty and comfy feel is great, although a bit on the sporty side. On 18" wheels the car feels pretty hard and sporty, still managable for everyday driving, but on rough roads you would want a softer setup.
So it depends on what you want really. B6 has a montube design and is therfore longer lasting, as much as I know.
Koni FSD (my first choice) are no longer availabe for 166 unfortunatley, but their life-span is short according to some users, so I do not regret not having them that much. But they do offer sportiness when you corner and comfort when you are going over bumps, so I think they must be great for a car like 166.