Are you going for look or function? My personal opinion is that most OE fog lights are junk, both the housings and lenses so replacing the bulbs will do you little. I run PIAA 520's with the ion crystal bulb and I'm happy. From past experience though, you can't get any better than a yellow projector beam for true fog and snow performance.
I have ddm 3000k in my fog lights, they work great, they look bad ass. It depends if you want functioning fog lights, or bright 5000-8000 that color match your low beams..
I'm all about function, I spent 100's of dollars trying to color match my fogs to my HID's on my acura, on the 4Runner I went for brightness and light output. For driving and treking around I much prefer white HID's