Which one is the best company in digital cameras?

All of the major companies are good choices. Pentax, Nikon, Minolta, Olympus and Canon are all top level manufacturers. Some of the less expensive brands such as HP, GE, Polaroid and similar economy brands are rebranded merchandise from the same manufacturers. They give good service, but not generally on a level with the major brands.

Choose any of the above names with confidence, then decide what you can afford to pay and shop for features.