I have fielded many questions on metallic vs ceramic pads over the years.  This guide is intended to explain the pros and cons. Years ago, brakes were made with asbestos fibers.  Asbestos brakes were phased out, and the lining formulation was changed to one of two types: organic or metallic (including semi-metallic pads that are a hybrid between organic and metallic pads).  Organic brakes used chopped kevlar or fiberglass as a binding agent, and metallic pads included iron powder and fibers.  The disadvantages of metal fibers in the pad: 1) it expands and contracts to destabilize the binding agents, 2) it promotes clumps of high density areas in the pad that can cause noise and grooves in the rotor, 3) it facilitates conduction heat transfer to the piston that can cause brake fluid to boil.  The advantage of metallic pads is that it had much better fade resistance than organic pads at high temperature.  In the 80's, Akebono developed ceramic pads that really elevated friction pads to a new level. Ceramic pads are still an organic pad (free from asbestos) but with much better brake performance. Ceramic has the advantage of high thermal dimensional stability and improved pedal pressure sensitivity, i.e. the driver does not have to press harder on the pedal to stop at the same rate as the brake temperature increases.  Ceramic pads tend to be quiet with great all-around performance.  

Most OE vehicles now come from the factory with ceramic pads. In general, I recommend ceramic pads for most street driving, and metallic pads for racing, police pursuit or commercial truck applications.  There are many different brands of ceramic brakes, and some manufactures sell ceramic brakes that have metal in them. A true ceramic brake pad has no ferrous metal in it.  If you are not sure if you bought a true ceramic, just take a magnet and see if it sticks to the lining. There is a wide range of brake performance with different ceramic brands. It is important to purchase pads that are close to the OE brake characteristics. Some ceramic brands that have tested well include Akebono, Power Stop Evolution, Bendix CT and Satisfied.  Some ceramic brake pad brands tend to be very abrasive on the rotor. A high quality rotor is recommended with ceramic pads. For maximum safety, it is also important to consider other aspects of the brake system.  Brake performance is most affected (in order) by:

1. the tire condition
2. the brake pad
3. drilled rotors 
4. stainless steel brake lines
5. brake fluid

Brakemotive ceramic pads and cross-drilled rotors