What is the most efficient heating option?
Reduce the need for an active heating system by improving the design of the dwelling. If the heating load in Thermal Comfort is sufficiently low and it is realistic to have no heating, then the highest-scoring option is "no heating to be installed".
If there is a heating demand, then gas fixed flued heaters with a high star rating and air-conditioners with a high efficiency or star rating will score well.
Gas-fired hydronic systems are also efficient and score well; the pipes should be properly insulated.