Love the handles! As much as I love the brass I think go for the black and let the splashback stand out

I also love the brass but would worry about them showing finger marks so would probably go for black on balance.

Black!!

We just installed our new showroom in Nailsea Electrical in Bristol and had a very similar dilema. The shaker cabinets are Farrow and Ball Down Pipe with a concrete look neolith worktop and brass splash backs. We put cast iron knobs on but now they are on we were thinking brass knobs may look better. I think the brass handles could look really cool with the splash back. Have you considered aging your brass to reduce the 'Bling' look?

brass or maybe even copper as a contrast

I'd go black. You are more likely to get fed up with a lot of brass in the long term. You could pick up the brassy colours with brassy accessories around the kitchen. Even though I love brass, I agree that brass splashback and brass handles could overdo the 'bling'.

The brass are fantastic! Will fit the kitchen perfectly

The brass look fab, they are a real showstopper! https://www.abbeywoodfurniture.com