Since your other thread with my response disappeared, I will rewrite it.
The brightest halogen you can get is the Philips HIR2 9012. It's rated at 1700 Lumens on low beam, which is higher than the Silverstar Ultras on high beam and VERY close to the 1800-2000 Lumens of HIDs on low beam.
The next brightest is the Philips X-Treme Power, which is about 1500 Lumens on low beam, which is a little brighter than the Silverstar Ultras.
Here is a pic comparing the Philips X-Treme Power and the Sylvania Silverstar Ultra side by side. Philips on the left, Sylvania on the right.
The Sylvania Silverstar Ultras are really popular, but aren't really much brighter than stock and they have a very short lifespan. On average, you'll only get about 2 years worth of use out of a set, but don't be surprised if they last less than 1 year.
They are technically rated at 1500 Lumens on low beam, but they also have a blue tinting on the bulb which reduces the amount of useable light that they emit. When tested under real world conditions, they come in closer to 900-1100 Lumens. They seem to be brighter because of the blue-white light vs the yellowish light of others, but they aren't really. It's more of a placebo effect than it is an actual increase in the amount of light. It LOOKS whiter, and most people equate that to brighter.