There are many types of metal roofs available today. While we are happy to help you in your research, let me try to break things down as simply as possible. First, there are painted metal roofs and unpainted. The unpainted ones are natural metals such as copper and zinc. Steel and aluminum roofs though will have some sort of paint finish in most cases, even if it is just an inexpensive clear coat. The clear winner in terms of the best paint finish, with no better technology on the horizon, is the PVDF finish, often sold under the trade names of Kynar and Hylar.
Next, there are roofs with exposed fasteners and those with hidden fasteners. The exposed fastened panels are often corrugated metal panels used in the metal building and agricultural markets. Exposed fasteners can be prone to loosening and leaks and they also do not allow the metal to expand and contract with temperature changes. Most homeowners will choose metal roofs with concealed fasteners that have good allowance for thermal movement of the metal. Next, there are vertical seam roofs and there are metal roofs consisting of interlocking modular panels. Those panels may be formed to look like roofing materials such as shingles, wood shakes, slate, or tile.
Our advice is to choose the look and product attributes you want for your home, locate a manufacturer, and then ask them who in your area is experienced at installing their products.