Well I personally am in love with lacy undies. http://fab.com/product/rayon-lace-underwear-blue-moon-400265
They just are really girly and I find them very comfortable and breathe well, but really its all about your personal preference lol Different people like different looks and feel comfortable in different styles and materials. I don't think there's such a thing as a best color undies to wear, although you wouldn't want to wear black underwear under a white skirt O-O Just making sure that your underwear don't show up through your clothing is important as far as color goes xD
Well, underwear that's good for your ladyparts are cotton and not tight on the crotch, so no thongs or any of the sort. If you're not concerned with that then its a matter of preference. Personally I find cotton boy shorts most comfortable, I find Lacey underwear to be the prettiest, and I hate the way thongs feel even though I do still wear them.
As Bathory said, cotton is the best for your lady parts. I personally love cotton boy shorts with lace detailing. I used to hate thongs but now I really like them. I love Victoria's Secret undies. It all depends on personal preference, there is no best kind or color of underwear. It's totally up to you to decide that.