Here in Lancaster county, we get quite a bit of fog in the early morning. Since the JK is my wifes DD, I chose to go with the black PIAA model 510 fogs in ion crystal. She loved the things for early morning driving. When set up properly these fogs give a 60* spread and reach out nicely with the yellow color that breaks right through the fog. They've been on now for a little over a year, but since they sit atop an AEV bumper, the 4" lamps looked pretty small, and although we liked them at first, they seemed to get samller and smaller everytime we loooked at them. Just got a new set of black PIAA 520's, and since they're 6" they look much better on the JK. Again I got the fogs in ion crystal, and they give an even better spread at 95*, with even more light at 85W H3's as compared to the 55W H3's on the 510's. I run black IPF model 6313's on my XJ, and the've been a good with no visible rust for almost 8 years now. They throw a good fog beam, however I moved to the PIAA's because of the cost difference. The IPF's are about $40 more for the 4" model as compaired to the 6" PIAA's.
As for the Hella's, I ran a set on the XJ early on, however was not happy at all. Although they were OK as far as light, the things started rusting just after 3 years. Guess you get what you pay for. At any rate, I'm sold on PIAA's, and they have a very good selection.

 

I have KC's. 3 sets of them. One set fogs, one set driving, one set long range spot. One set ws a gift, one i bought, one I parts traded for.
I recieved the gift ones first. So when i bought a second set, i just got them to match, and they where cheap at the time, third set i just lucked out on the swap.

I had Fog lights first, they are the most usefull, and of the three, they get the most duty. The driving lights I use as well, just not as much as the fogs. THe long range spots i rarely use, but when i need them they are a godsend.

I had KC's on my old truck for years, never rusted on me.

The original KC fogs on my bumper now, are beginning to show rust on the little bracket the light mounts into. They are about a year old, and although disappointing, isnt a big deal to me, ill just scuff up the brackets and squirt them with some primer/rustoleum and theyll be good to go. Probably do that today as i want to just paint my drings in place anyhow.

I think most of the lights mentioned are good lights. The pattern you choose is kind of dictated by your location/intended use. I have both(3 with the spots) because i am a lightHO, and i actually do use them all. Price to me wasnt really a concern because of how i ended up with them, but would be if i was going out of pocket on them now. i wuld LOVE a set of IPF's but they are just out of my range at this time.