There are 3 benefits of a quality cold air intake.
1. Quality filter. Stock paper filters are nice because they are cheap, but they dont flow as well as a quality oiled or dry aftermarket filter
2. COLD air intake - you want to be sucking in cold outside air, not stagnant engine heat. The 2 best in this reguard are the Vararam and the S&B. Vararam pulls air directly from the front of the grille and the filter is sealed off against the hood to keep engine heat out. Once that air comes in the grille and into the filter tray, it has nowhere else to go but straight down your throttle body. Next best would be the S&B which pulls air from the fender like the factory airbox, and also has a downward facing scoop that pulls in air from under the bumper. This is in front of the engine, so it will not pull in any engine heat.
Some of the cheaper kits like K&N dont have a closed filter and will bring in some of that engine heat. Volant is nice, but it only pulls air from the fender like factory, so I would take the S&B over this.
3. Cold air intake kits replace the turbulent accordian shaped factory intake hose with a much smoother flowing, smooth intake hose. The less resistant you have on the air coming in, the better.