S7-LN is best for a beginner, with the low power usage and also the cheap price. Also has a psu included so you don't have to buy one yourself. This thing was practically made for a beginner, and has the same specifications as the S7 except less chips and less power usage. It's also available directly for sale from Bitmain, and will actually make you some money after the halving, but not enough to roi. If you're loking for ROI, try the S9. It doesn't guarantee ROI, but it's the closest thing to it at the moment, since avalon gave up 16nm, and bitfury is taking forever.