Halogen vs. Sealed beam

I have decided to go with daylighters on my rig, but now I am confused about which ones to go with. There are so many options. Does anyone know the difference between Halogen bulbs and seald beam bulbs? Which ones are better. What would be the best choice for wattage? The 100, 130, or 150 (I believe only sealed beam comes in the 150.) I plan to run 2 on the bumper for now, and possibly move them to the roof and add 2 more later.