What kind of material do you use for a kitchen countertop?
"Best" depends on what you think is best for a particular purpose. Nothing looks as elegant as marble, but it is easily damaged, so if you don't need elegance you don't want marble. Granite is popular. Stainless steel is almost indestructable, but it makes the kitchen look like a machine shop. Plastic laminate is cheap, pretty, and durable so that is the usual choice for a residential kitchen. Some people have concrete counters, stained so they don't actually look like a sidewalk. Some are tiled. Endless variety.
If you don't have a lot of money you are going to use premade countertop, whatever the local store has in stock.
My recommendation is soapstone countertops. They are durable in terms of stains/spills and easy to clean. Soapstone looks similar to marble but is usually limited to shades of white, black and grey. However, it can be scratched by things like knives and such. It is smooth and cool to the touch, also similar to marble in that way. It is also a lot cheaper than marble and some other kitchen tops.
It all depends on what your kitchen looks like and what you think it needs/goes best with it. This is just my personal recommendation. :)