There are so many types of bakeware available today, it can be difficult to tell which ones are best for which foods, and how to care for them.
A true cookie sheet is totally flat. Occasionally, you'll find a sheet with one or two edges bent upward to make it easier to handle. Some cookie sheets have short, raised edges on all sides and may be advertised as a cookie pan. This is actually a jelly roll pan, and is best for thin cakes or bar-type cookies.
The best cookie sheet is a shiny, all aluminum flat cookie sheet. The shiny surface helps to reflect heat onto cookies and promotes even browning. The same is true for cake pans. The best method for cleaning aluminum bakeware is with soap-filled steel wool pads. To keep your aluminum cookie sheet shiny, DO NOT put in the dishwasher. Be sure to clean the bottom as well as the top. If the bottom is not cleaned regularly, over time it will become dark and discolored, and can affect your baking results.
Dark surface and non-stick surface bakeware tend to overbrown the bottoms of baked foods like cookies and biscuits. To help avoid this, reduce the baking temperature by about 25 degrees F.
Air-insulated cookie sheets are popular and can give good results. However, they can sometimes warp, and since some types can't be soaked in water they can be hard to clean.
Baking stones yield nice browning results, however they must be kept seasoned (a nicely-oiled non-stick surface from baking high-fat foods). And you should never wash baking stones in soapy water as they are porous.
Glass bakeware is acceptable, but does not give the browning results of shiny aluminum. It is easy to care for and lasts forever.