I am based in the UK and have used a web host before in the USA. I ran into a problem with the maintenance cycle the support technicians used. They used to take the servers down for maintenance in the middle of the night on fridays to install security updates and do general maintenance. This was fine in principal but 3am where the servers were was 10am where I was and was one of my busy periods on the site. I think it is best to get a web host who is where you are geographically. That was when you have a problem at 9am it isnt 2am for the support guys.