probably skeincoin.
17M coins. 11M mined. PoW. Skein-Sha256. price per coin 35 sat. mining dif between 5-20
--Sheepman solved a block on his Pi2--
For now, that looks like it beats The Ideal Reserve by the SSL and domain, but if difficulty goes up rendering the device useless, the entire device must be considered a cost. It will take a long time for the hardware requirements of The Ideal Reserve to exceed that device.
So , you can buy some hashing contract at the beginning, then no need hardware investment at all .