In my opinion anyone who pays for or is considering paying for a broadband download speed of more than 2Mbps is wasting their money.
Stick with the cheapest option - which is normally about 2Mbps - This is a perfectly acceptable speed and you dont feel that you are waiting for pages to download.
Even if you do pay for a higher speed its very unlikely that you will ever achieve that speed since so many factors have an adverse effect.
Some popular web sites for instance restrict their download speed in order for a greater number of users to get connected. And of course your distance from the exchange that you are connected to has probably the greatest effect The further you are away from the exchange and of course the number of users at any time will have a very great effect.
Think before you part with your money