Last night I did a fresh install of Sierra - I downloaded it from the App Store, created a bootable USB drive etc.
I didn't check the build number my MBP 15" came with but after the fresh install it is 16B2657. Shouldn't it be 16B2659? At least that one seems more recent to me...
I did my fresh install using the built in macOS Recovery (https://support.apple.com/en-us/HT201314), which downloads a fresh copy from Apple. It gave me the most recent build, 16B2659. So it looks like that's the way to do fresh installs atm.