The upper tier of roofing materials in terms of quality and looks are tile and slate roof shingles. Both tile and slate will last a long time due to the strength of their material. Tile is made out of baked clay, while slate is either stone or a synthetic material.
The most recognizable form of tile are the red Spanish s-tiles. These are a traditional and classy look, but tile can come in may more designs as well. Some tile is even made of concrete instead of clay. Concrete can be molded to look like other types of roofing materials. Both forms are very resistant to weathering because of their density. The only real weakness of tile is that it is brittle and can shatter when people walk on it. However if for example a tree limb falls on a tile roof, it will only break a few tiles. Compare that with having to call a Denver roofing company to completely replace a thinner asphalt shingle roof.
Tile can withstand fire, hail and other adverse conditions well, although it is very heavy like slate roofing. Slate has many of the same benefits, but it is the most expensive roofing material. Some at the Denver roofing company say this is because they look better, however the real reason is because slate is really made from stone. It is a hard to gather natural material.
The main benefit of using real rock is that it lasts almost forever. It may cost 10x as much as asphalt shingles, but slate roofs will last 10x as long as well. They require much less maintenance from a Denver roofing company over that span as well. Like tile, slate is very heavy and requires a sturdily built roof to hold it up. Not all roofers are familiar with slate.
One interesting factoid is that light colored roofs significantly reduce the amount of solar energy absorbed. This keeps the house cool in the summer, and it also brings the effects of global warming by reflecting heat back out into space. So in warm climates pick a lighter colored tile if possible. Slate is losing some of its popularity because of the price. There are new synthetic slate roofing materials that are made of either slate dust or cement and fiber resin. They are slightly cheaper and retain many of slate's good qualities.