Our previous kitchen had stainless appliances from Thermador, Kitchenaid, DCS, Miele and ULine. They all look fine together, even with slightly different handle styles.

For the remodeled kitchen I integrated/paneled some of the appliances, but the new Miele, Wolf and ULine stainless look fine together. It really isn't noticeable. Just make sure you get the standard stainless and not the "specialty" ones which are slightly different by brand.