S7s and Avalon6s are now cheap enough too to start mine with it, so i would recommend to buy some. Some second-hand asics to help other miners get their ROI.
I'm speaking seriously. Not all of them has "nearly-free" electricity...
People say that Avalon6 are more robust. Personally I have 2 S7s of different batches for about 4 monthes, both are OK. My fellow has 20+ of S7s, all are OK too.
Ethereum mining is getting less and less profitable, so I would not advice to start mine it. Unless topicstarter has a plans to continue mine with GPU rigs (at Nicehash or directly mine any forks).
Just for fun I would set a CPU-rig with some cheap CPUs like FX-8350.