The "best" setup is what makes sense for you. If your electric costs are low, and you value reliability over power then I would go with the Avalon 741's. You could even use some of the older models and still be making money. If you ,like Jeremy Clarkson want " More Power" then for now you will be wanting to grab an S9 and rolling the dice on what works and for how long, you might be one of the many lucky people who get a fully functioning unit for the long term, or you might slowly watch bits die off here and there.
Best bet is to research the current equipment being offered by the main operators at the moment, and pick one after researching them. This forum is full of info, and very similar questions.
Anyone have a mining rig they wanna sell to me?
You should look in the marketplace to find equipment.