Many people swear by their natural gas tankless water heater. Millions of families around the world get all their hot water this way - they never run out and they never pay for more than they use.
There are plenty of tankless waterheater systems on the market, and they run on fuels other than natural gas - liquid propane gas and oil for example. But natural gas that is piped to your home has at least one clear advantage over these fuel sources - no delivery worries.
A natural gas tankless water heater is more convenient than almost all the rival systems, except, perhaps, electrically powered systems that simply need hooking up to the power supply.
Gas on demand hot water heaters however work very quickly (gas is hot as soon as it is ignited) and can handle quite a lot of demand if you buy a suitable unit. They are also cheaper to run than just about any other system, thanks to the cost of natural gas and the fact you only heat the water that you use.
If you are in a natural gas supply area then tankless gas hot water heaters are something you should consider very seriously.