CHIME NOISES INTENSIFY
Now based on designs, I'd have to go with Whirlipede. It's like a rolli polli (oli) and looks pretty awesome, I mean who doesn't like a bug-tire? Garbodor is cool, but idk the pigtails are just a little weird haha. Whirlipede definitely has garbodor beat in terms of shiny coloration, as it's way cooler with those blue rings! However, I think Garbodor is MUCH better in anything concerning usability. I haven't used garbodor ingame, but just it being fully evolved gives it a major advantage. And if they were to battle, I think garbodors movepool is better (along with stats) so it'd be victorious. And garbodor is MUCH better competitively, as whirlipede always dies after like 2 hits even with eviolite, while garbodor can stick around to set a bunch of things up.
So my vote goes to garbodor!