I picked Whirlipede obviously because I hate Garbodor's design. Also, Whirlipede has solid Defense and its Bug-type can be helpful against a few things. Garbodor obviously has much worse abilities too, while I had a better time with Whirlipede in-game.
Also, I do think Whirlipede will firm better competitively as well, especially with a Black Sludge or Eviolite equipped. Garbodor's only good for setting up Toxic Spikes, and that's all.