From what I've seen, I'd say Beyblade. It makes no sense how plastic spinning tops are able to attain magical animal powers and save the world. The characters also act as if it will cost their life, if they lose a match. The characters clearly are madly obsessed with their toys.
And they never explained where did the magical power comes from.
But at least they have magical powers.
"Let's and Go!" anime series involves small toy cars with no magical power whatsoever, but are somehow able to respond to and perform their owner's orders.
And there's no possible explanation on how did that can happen, because it has been clearly shown that most of the cars in the series have no controller, let alone a mechanical system with AI in it. So it should have been impossible for the cars to be able to "listen" to orders.
There is a chip, but said chip is clearly mentioned as being used only for some kind of ID recognition on a tournament as well as to improve speed. Not for making the cars able to "listen" to orders. And the chip appeared only after lots of episodes into the series and only on one tournament, so it clearly not for explaining the cars' ability to "listen" to orders.
Also, L&G suffers the same problem as various anime meant to promote toys and games : they lack a clear plot, as they focus on promoting, not telling a great story.
Yu-Gi-Oh! manages to put up a decent plot while still promoting cards at the same time, but L&G and the first Beyblade anime series are often filled with "battle of the week" filler.