dodgyshirt - it's also possibly the worst in the country, half joking and half serious. You get what you pay for, you can get good vsalue by buying unknown brand names but equally you can get a load of rubbish. I purchased a cheap monitor from Staples and the quality was rubbish.
To answer the question I prefer square or even portrait monitors, this is especially true if you look at the web often as they are still designed to look good in normal mode rather than widescreen. I have a Samsung Widescreen TV as my monitor and while the picture is fantastic it's not great for looking at websites.
At work I have two monitors, one is landscape and one portrait. The portrait one allows me to see much more of a web page than if I have it in landscape format.
But as others have said very much depends on what you will be doing with it, if it's watching Films then widescreen, if it's general computer work it makes little difference.