"Smart" depends on what qualities you value as 'smart'.
Leaving the definition up in the air is a hazard.
If 'smart' means best deal, the $2,000 Magnepan 3.6 is the better deal if you are not so well off.
And would not be kicking yourself for not getting the 3.7's next year.
If MONEY is not a big issue for you in this deal, then Damn, get the 3.7s ... You will NEVER need to worry about it again.
So: be cheap or 'frugal' and buy the 3.6s. IF you really are a frugal person, then you will be very happy with them.
On the other hand if you are just asking because you really do not want to pass up the 'best deal' And 'best deals' are something you cherish.. if the money is not a big deal... Then the $4,000. 3.7s are "THE BEST DEAL" because no one is getting that price on 3.7s.
They are a better speaker, and newer. and cooler.
Now if you could buy a pair of 20.7s for $10,000. .....
OK?