Fact-check on metal roof quote by roofing company
Metal roofs are not fragile, that's complete baloney.

The gold standard for long lasting roofing are standing seam copper, slate or quality tile. Standing seam steel won't last quite as many decades, but it's good.  All of these have high up front cost, but will save money over the long term.  Composition roofs must be thrown in a landfill every few decades.  Yes, metal can dent with heavy hail, but a few dents is not failure by any stretch.  And if you're in a fire prone area... metal is really hard to beat.

ArrowLine Slate Roofing is a good product for a slate look steel.

A lot of roofers only install composition shingles, it's all they know.

If you go with true rock based slate, check out http://www.slateroofers.org/

Re-roofing is also a chance to get an energy and building performance evaluation done.  There's a lot of detail on venting and deck top insulation that can be fixed as part of roofing job  --- saving energy and cost and increasing comfort for the life of the building.