There are two main types of metal roofs, exposed fasteners and hidden fasteners. Exposed fastener roofs are installed with rubber grommets and screws through the top surface of the metal. There are several different profiles and colors of metal available. Hidden fastener roofs are called standing seam metal where the metal panels are clipped and screwed to the deck and the next panel is attached over the clips hiding the fasteners. Standing seam metal roofs are more expensive than exposed fastener roofs.
Both roof systems are excellent choices for a roof system. Exposed fastener roofs will ultimately need to have the rubber grommets replaced since they degrade over time. Standing seam metal needs no maintenance over its lifetime and many people consider it to be more visually appealing. For those reasons standing seam may be a better roof system. The metal itself and the finish is available in both types of roof.
Metal roof panels that are provided from a reputable manufacturer will last 35 to 40 years and sometimes longer. One of the important elements that determine the life of the metal itself is the type of finish applied at the factory. There are also many different, appropriate underlayment choices for metal roofs which will be a factor in determining its longevity.
Metal roofs are considered a premium roofing material, therefore the initial cost to install a metal roof is higher than most other roofing materials. There is a correlation between roof life and cost. However, when you compare the lifecycle roof cost, meaning the cost of the roof vs the life of the roof, it is actually not more expensive than most other roof systems.