I personally would go with Karis for your kitchen. We were debating between LG Aura and LG Karis (We used very similar colors to your cabinetry choices - white cabinets and a light gray island) and ended up going with Aura, but I still love the look of the Karis. We had looked at the Quartet also but in a larger slab thought it was a little boring. I think the Aura is a little grayer while the Karis had a whiter background. We have had the Aura installed for about 5 months now and love it. Easy to clean. In our experience, LG is a great product and looks really nice - we get a lot of compliments. (Excuse the mess in the pictures, I have a 1 year old running around my kitchen like a tornado! But to give you an idea of how it looks)
Q