Best software to build a database

I need to build a database to keep track of my contacts and do the follow-up of all phone calls and proposals send to clients. What's the best tool to do it? Do I need a specific software? Which one's the best?

Tks!

Have a look a Bento for Mac.
Mac Software | Bento 3
They also make FileMaker, it is an extremely advanced database management tool and has a price to reflect it.
Database Application By FileMaker | FileMaker Pro 11