The finest sherry wines come from wineries near Jerez de la Frontera in Spain. Amontillado sherry is the gold standard of sherries.
Amontillado sherry is a dry sherry, more concentrated than manzanilla or fino sherry. It is less dark and less concentrated than oloroso sherry. Like all sherry wine, it's from the Jerez y Manzanilla region of Spain. When you're looking for a classy and smooth-tasting aperitif to serve to friends, amontillado sherries are good choices. Some of the vineyards that make good Amontillado sherry are Hidalgo, Gonzalez Bypass, and Valdespino.
I love this video about the tasting of four different types of sherry on a California rooftop. The wine gourmet talks about the process of making sherry, including Amontillado sherry, as it's done in Spain.
The process of making Amontillado begins with "flor", or biological aging. As the flor's food supply dwindles, it dies and oxidative ageing occurs over a period of time. The desired result is a smooth sherry with a somewhat nutlike flavor. Wine gourmets have used terms like "walnut flavored" and "caramel essence" to describe Amontillado sherries.