Reliable and Ultra Secure Internet Connections

What would you name as the number one advantage of a 3G wireless mobile broadband connection of Wi-Fi? Obviously it would not be cost. Very often a WiFi connection can be found that is free. And Wi-Fi allows more than one user to tap into the network at a time. Such as when you have your landline based broadband sent into a wireless router at your home. Dongles for laptops allow one computer to operate at a time.