If pricing were part of it then everyone should have a low rating! Nothing being sold at retail will make a positive ROI even with free power.
And that makes any guide at this point useless. This might be the end of this portion of the forum considering it was the user coming here to discuss hardware that made it relevant. As time goes on there will be no more interest or users.
Nobody could ever guarantee ROI for any miner, as bitcoin could be worth 1$ or 1000$ tomorrow, and many other unknown parameters influence a possible ROI.
It is highly unlikely that a large amount of hashpower would be maintained without the possibility of ROI, therefore increasing the chance of already bought equipment to achieve ROI.