Tankless water heater water heater will always take less electric than tank, you leave the tank on or not. It sucks huge power instantly when you open the tap but them stops. Overall use can never be more than the tank.
As a brand name, Steibel Eltron is rated as best electric tankless water heater. It is German and built for cold climate. Malaysia is no cold climate so it'll do much better. Looks very small though. You need to question its kilowatts. The more it has, the more hot water it can give you instantly.