The S5 is most likely useless unless you just want to buy it to learn (cheaply). The S7 will be small profits but an s9 or Avalon7 are the way to go right now. Of course that means more money upfront. At that rate it'll be ok most of the time to mine but that would depend on where the difficulty goes over the next months/years.

Check any calculator out. Here's one http://www.coinwarz.com/calculators/bitcoin-mining-calculator