Espresso concentrates everything in a coffee: the sweetness, and the faults. That is why most cafés use a blend for it.
What to look for
A medium to dark roast, if you drink it with milk
Roasted between one and four weeks ago
Beans that look even in colour
Our House Blend was built for milk drinks. For espresso on its own, try the Single Origin of the Month and grind a little finer than usual.