There are many types of screwdriver sets. Some just include a particular type such as slotted or Phillips in various sizes. Other sets include a combination of types such as slotted, Phillips and TORX.
For working on small things, a precision screwdriver set would be required. A TORX screwdriver set would often be needed for automotive work.
The quality of screwdriver sets varies greatly and of course the better quality sets costs more. The key is to know the intended use. An inexpensive screwdriver set may be perfectly adequate for the occasional home repair while the professional user would definitely want several high quality screwdriver sets.