USB gamecube controller or gamecube controller + adaptater ?

[Memès_land]

Hello.
I'd like to play GameCube games with Dolphin, and I want to play with a GameCube controller.

But I don't know if I should buy:
- A GameCube controller USB (I think that I saw that it was not recommended)
Or
- A real GameCube controller with an adapter "Mayflash 4-port adapter" (that work better with Dolphin)

Thanks for advance !