I prefer Antminer s7 on Avalon 6.
The new Antminer S7 Plus is much more efficient.
There's not a S7+ version, am i misunderstanding?
And now the latest batches of S7's have the same efficiency as the Avalon6, so not the only reason to stick with S7 is the GH/$, since the Avalon6 has a much better build quality.
You are right, there ain't any S7+ version...
The latest batches of S7 are cheaper, and they are more efficient than Avalon 6 in terms of Hash rates, while Avalon gives you 3.86 TH/s, S7 gives you up to 4.75 TH/s which is way better than Avalon...
What will you do with the build quality since you are going to get your ROI in less time with S7???
And both are machines, so nothing comes with a guarantee here (in few means)...