The flashlights don’t differ much in terms of their impact—the materials, energy, and shipping costs are similar (and in fact, many flashlights that take a rechargeable battery can also take conventional throwaway batteries too). But the batteries have a significantly different impact. Assuming you recharge your flashlight more than 50 times, the overall impact (including air pollution and waste) will be lower than using a flashlight powered by disposable batteries. No matter what kind of electronic you choose, it's also important to recycle batteries and other e-waste, don't just toss it in the trash.