The answer to 'tankless water heater vs tank water heater' is that tankless water heaters are generally more energy-efficient and take up less space, but have a higher upfront cost. Tank water heaters are less expensive to install but can be less efficient and require more space.
Tankless water heaters heat water on-demand, only using energy when you need hot water. This can save you up to 50% on your water heating costs compared to a traditional tank. They also last longer, around 20 years, and take up much less space since there's no storage tank. However, tankless models cost 2-3 times more to purchase and install than a tank heater.