I don't think there is much difference between the 2016 and 2017 models except for minor spec bumps. I actually have the 2017 512gb ssd and 4gb radeon pro 560. It is work issued and replaced a 2015 model. It doesn't feel a whole lot faster than the older one.
The biggest difference to me in the 2015 and 2017 is the graphics card. The newer one runs much cooler. Even in this, there is little difference between the 2017 and 2016.
7 years and not used 300gb of data is unimaginable to me
There are a few things to consider and only you can decide:
If you don't think you'll change your data usage pattern (i.e. 300gb in 7 years) then you probably don't need 1tb on a laptop.
If you absolutely positively WILL (not just thinking about it someday) get into video editing, know that this takes up a lot of storage (I'm sure sound production is similar but to a lesser extent). Even if you plan to archive the videos to some external hard drive, you'll want to work/edit from the faster internal ssd. So bigger ssd is better.
7+ years is a long time. Check how long apple supports machines recently. This might give you an idea if the older model will still be supported toward the end of your planned ownership. The 2016 model is already 2 years into its support cycle.