You gotta be careful with those halogens that claim 5000K+ and give you a blue-white light.
1) They typically burn out really quickly, especially the ones that claim higher color temperatures and increase the wattage.
2) You are going to wish you didn't have them when it starts raining at night and you can't see shit.
I bought the GE Nighthawk Sport bulbs and they give a slightly whiter light and better visibility than the stock bulbs (but not by a lot).
Before I settled on the Nighthawk Sports I had Philips Crystalvisions but there was almost no difference from stock. However, I have been told Philips Diamondvision gives you a much whiter light but you need to buy them off eBay since they aren't available Stateside. I would have tried these but I didn't want to get stuck with $60+ bulbs if I didn't like the result.