For myself I have always hosted in the location of the head quarters for a company, for example an Australian Company requires Australian hosting, an international Company that has offices overseas but a head office in Australia would also require Australian hosting. Another example would be an Australian government they definetly should never be hosted outside of Australian soil…
If the company is based in UK then UK hosting, American then American hosting…
Why does this matter you say? Page speeds and packet loss are one thing… the main thing is with Data Jurisdiction. The data on the website is controlled by the jurisdiction of the country it is held in? but that is not important you say why should i care? because if anything happens to the site, or if there is any legal concerns or cases etc that involve the data all of a sudden you are dealing with Australian jurisdiction due to the fact the head office or government body is in Australia and you are also now dealing with for example American jurisdiction as that is where your data is located.
Another point here to raise is each jurisdiction handles data and also access to your data differently, some countries for example state that your data can be accessed by a legal third party at any time of the day and also without any warning to you. They can also shut down your site for the same reason, and this can happen as it has done in the past because your hosting company in America has had a security breach and the server that holds your data has been found to also be harvesting DDOS attacks… yes this has happened to Australian and other companies..
Anyways these are the reasons why you should also have the due diligence to your clients to inform them if they are hosting off site that there data falls under jurisdiction X or jurisdiction X Y and X…
Ninefold who is an Australian cloud hosting company has built a great info-graphic and I would recommend walking it through with potential clients… http://ninefold.com/data-jurisdiction/infographic/