I think it's beyond question that you should continue with your plan to do the graduate degree. There isn't an inherent advantage to studying in the US or the UK, but in your situation I think the US makes sense. As you describe, you are more familiar/comfortable with the country.If you end up returning to Afghanistan after your studies then the US network may be helpful (from a business perspective Afghanistan could have a lot of future potential, and I imagine that US companies are likely to get the development/reconstruction contracts).The advantage of studying in the UK is that it will add to your international and academic experience, so that you have an additional option for working in the West. Given that you have already spent 4 years in the US, the UK may add more at the margin to your experience.Beyond that, your preferred career/industry within the "business field" will determine the most appropriate schools to consider.