Use LED lamps whenever possible.

LED lamps (80 lumens/watt) are over four times more energy efficient than halogen lamps (17.5 lumens/watt). LED lamps are also more efficient than energy-saving lamps (50 lumens/watt). The situation is similar for lamp life and operating costs. Service life in hours: LED lamps 30,000, economy lamp 10,500, halogen lamp 2,000.
Operating costs for 1,000 hours in CHF: LED lamps 1.60, economy lamp
2.50, halogen lamp 10.- [1]

[1]: Energie Schweiz: Ratgeber Effiziente Beleuchtung im Kleinbetrieb