You may notice, if you go looking for a reputably refurbished one (at least in the States), that they can be difficult to find. Apple hasn't had them for a good long while and OWC will get a couple now and then which are snapped up almost instantly.Would buying a 2015 15" be a bad move in 2017? Seeing as how they have a fourth generation Intel CPU?
My guess is that a lot of people have looked at the 2016 systems, laughed, and are buying refurbished 2015 units as fast as they become available, instead. Or, they're returning their shiny new 2016 systems (Apple has loads of refurbished 13" ntMBPs available), and stepping back a generation. I did that with my very first MBP, after stupidly being a first gen adopter. Went back to a PowerBook G4 in a real hurry.
If you want compatibility for displays as ZapNZs mentioned then go with the 2016. Otherwise, the 2015 is still a fine machine, if you can get your hands on one. And you can swap out the hard drive. Plus have money left over.