I could light up reflective signs two miles away. But from not having the full spectrum of light, a lot of darker objects simply were not as visible. So I use white lights for their benefits the majority of the time. Some people prefer amber lights for more severe weather, and, obviously, for much less glare off of snow. But to me the disadvantages outweigh that benefits.
Bigger lights are, all other things being equal, better.
More reflector area reflects more light. Bigger, better lights do, however, cost more. Round lights are better than square ones with an equal area because the corners in a square lamp are sacrificing area. It isn't for the aerodynamics that rally cars have rows of big round lights across the front. Projector lights have the bulb sitting way in the back with an ellipsoid reflector behind it.