I came across a useful article in the paper (real estate section) the other day about roofing materials:
Composition/asphalt shingles are the cheapest and most popular material (85-90% of the market). Prices usually depend on lifespans and warranties. Not much maintenance, if any.
For more money, there are wood shakes or shingles; but there's a lot more maintenance involved; and there's the fire danger. And a roofer told me some years back about the critters that live in them, including roaches and scorpions, making them not much fun to work with (when reroofing or doing repairs).
Next up in cost and durability is metal. Prices vary depending on the metal (usually aluminum) and the roof style.
Top of the line materials include clay and slate; and they're heavier; and you have to decide about them ahead of time (when building--unless you can retrofit). Clay tiles are fire resistant and last about 50 years. Slate may outlive the house.
I'm sticking with shingles, though we thought about metal because of the style of our house, but shingles were more affordable; but oh, that gravel! Clean out your gutters!!.