IMO, and as much as i dislike Bitmain (but at least that is cured with Braiins OS) it is the better choice here, and because its used thats money they won't get anyway.
As the OP has stated, he has very low elec cost, so going for a lower hash rate wont be best for him ...
Well, since I have access to cheap electricity, efficiency is the last thing I care about.
Importat factors for me are being cheap and having higher TH as well as reliability and durability inorder to have better ROR , that is why I am not thinking about M20 , M10 or cutting edge miners, with same amount of money I can buy few low efficiency miners which will sum up in more TH just I need more space to put them which I am ok with it now.
Though I think this thread has finished - he seemed to have pretty much decided.