Which power supply setup do you prefer?

So I want to buy some AA's and power up my Tamiya twin motor gearbox.

I would go for B, because A will discharge uneven. But B will discharge equal. The only problem is, that ONE DC motor uses max 3V. So when only ONE is active, it will take a punch of 7,2V instead of max 3V

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So which of these do you prefer? A or B?