Choosing the right beer line is very important to keep a balanced beer dispensing system. The resistance of the hose counters the pressure used to dispense the beer.
This balance of pressure creates a well poured beer.
Lucky for you and me choosing the right beer line is easy.
For all kegerator applications use 3/16" I.D. beer hose. You will need 5-6 feet of hose for each faucet to create the right amount of resistance for your system.
Make sure you use actual hose made for beer in your kegerator. Don't cheap out and use plastic tubing from the hardware store. This will cause you nothing but problems.
Beer hose is food grade safe, it is rated to handle the pressure, and is designed for a consistent flow.
You can buy it by the foot or to make it even easier premade hoses with all of the fittings are also available.