I guess you have to take into consideration what you are using it for. Each of the high end versions of Seven have their special functions that are needed by specific companies for specific jobs. Albeit, the average home user can get buy with HP. The only reason for a home user going to Pro or Ult is for XP Mode, however, with Virtual Box, or VM Ware Workstation (Player) you can still basically have the same functions.
It comes down to what you want to shell out money wise.