For me, the best location for the task bar in Windows PC's are at the left and right side. Because, the width of the monitor is much larger than its height. This is my scientific explanation on why it is better to move your taskbar to the left or the right. The only disadvantage that I know is that you have to move your mouse more to the left or right edge of the screen depending on the location of your taskbar. In Windows 8, you don't have to point to the top-right or top-left corner of the screen to go to the start menu. The start screen is still there at the bottom-left. You don't need to adjust where to point your mouse when going to the start screen when you move the taskbar.
But still, it's you opinion on where is the best location for the taskbar. In my analysis, the left and right sides are the best location,. Regardless of where the start button is.