Because it's modeled on the default GameCube controller, the WaveBird is obviously suited for playing GameCube games. Unfortunately, Virtual Console games are much more hit or miss. Because of the button layout, some older games can feel pretty awkward. The large A button, offset by the smaller B, Y, and X buttons, feel much different from the old NES and Super Nintendo controllers, and the pressure-sensitive shoulder buttons must be pushed down all the way to register a button press.
Unfortunately, Nintendo doesn't offer much of a choice for playing older games on the Wii. The conventional design of the Wii Classic Controller is much more suited for Virtual Console games, but it won't play GameCube games at all. As indicated, the WaveBird, Mad Catz MicroCon, and other (wired) GameCube controllers can play both GameCube and Virtual Console games, but they're not nearly as comfortable for older games. The Classic Controller might feel better, but you'd be missing out on the greatest games of the last generation, including Metroid Prime, Super Smash Bros. Melee, and Star Wars Rogue Leader. In the end, we prefer a GameCube controller because of its support for nearly every old game in Nintendo's library. The best wireless GameCube controller remains the Nintendo WaveBird.