I would recommend going with a 4300k or 5000k AT THE MOST... for the maximum light output. You will still get that hint of blue you're probably looking for.

BTW, HID's pretty much suck in the rain. I recommend keeping the stock foglights as well, sometimes I use them in the rain and it definitely helps light up the road versus my 4300k HID's.. (all HID's suck in my experience, even stock HID's on BMW's, Mercedes, Porsche's, ETC.. (yes i have driven those))...

In short:
4300k for headlight if you can find them
keep foglights stock.