Editor for Multiple Niches

We need an editor that understands how to research, write in a couple of different styles, and knows that we should always ensure statistics, claims and data are accurate. Many of our articles need a slight tone adjustment, many need to adhere to a client's 'tone' or 'writing style' and/or follow their brand guidelines. In a sentence, we need someone that can take content and improve it from a B to an A+. That sometimes means that we need to add expert quotes, fresh data, or expand paragraphs that are thin. Other times the content is not in the 'best' order and just needs rearranged. We are looking for someone that is excellent at writing in various subjects; we mainly write about home services, construction, health and law.