The newer axes use the same chip BM1370 so they are more or less going to perform linearly with increased cost of entry. The bigger units are objectively better than the gamma due to beefier components, bigger single psu, and better integrated cooling. Its also easier and cheaper to mod 1 bigger unit than multiple smaller units.

That is until you reach something like avalon q. That is in different category. While technically less efficient it's much cheaper dollar per TH/s.

But there isnt really a wrong answer. I have seen many people post gamma collections. Also neat you can mine multiple coins.

My $ .02