You can get low energy bulbs that give the same as a 100w filament bulb, look for 35 or 40w.. A good thing with low energy bulbs is they do not generat as much heat as a conventional bulb, and the light is more blue and less red, getting near to day light once 'warmed up'.
Halogen bulbs; very Hot, dont last as long, and when one goes bang, It Goes BANG. Even the low pressure ones!
LED bulbs. In theory should last for ever, and I have hear that befor long you will be able to but lamps with the LED bulb hard wireded into the lamp!!!
The light can be a bit cold in colour, but they are also cold running. (OK they get a little warm but should not run hot). LED are also the only form of light source that will really save you money.
Every one that has changed a lot of lights to Halogen are often surprised that the electric bill is not as small as they had hoped. It may well be that the power comes out of the transformer at 12v, but there is stil 240v going in, and getting used.
Some stange way LED lights, just use minimal power, and still give a lot of light.
Personally, I like a good old floresent strip with a day light tube in the work shed, but on my desk I have an 'old fasion 80w clear bulb in a multi architec lamp.. (sod the expense) :-(