I love the look of the new slate appliances, but I also have to say nothing has arrived yet to displace stainless steel, so both are good choices. My complaint about the new slate appliances is only that they don't yet seem to be making a counter-depth refrigerator, and that's a deal breaker for me.

Stainless appliances have great staying power, their versatility with design styles and easy care have kept them at the top for decades. As far as slate, I have to say that this may be more of a trend, but still a good choice. It really depends on your style preferences. Best of luck!