As far as laptops go, you are better off buying from someone like Gigabyte, MSI, or Asus than you are buying something from someone like Maingear or Origin, since they'll charge double and sometimes triple the cost of buying one of the ones I mentioned.
As far as desktops go, there aren't any. Unless you're willing to fork out lots of money to do so. Big box vendors like Cyberpower, they have so many problems that it's difficult to recommend them. And then companies like Maingear or Falcon Northwest are readily available, but only if you're willing to fork out the money for them. However, the DIY option for desktops is there, where it isn't for laptops.