I'd like to clarify about the brakes. The HD brakes were available starting sometime 2012 for most trims, and then became standard for all vans for 2014 and newer. And I know as I had retrofitted HD brakes into my 2009 van and I did extensive research on this topic.
There are always revisions between year to year on some components, but I would say the 2012 to 2013 model year change was the biggest for the late 5'th generation vans and not much past that. This included graphics refresh for the radio displays going from light blue to black and also the screens, higher definition overhead screen(s) with the dvd player being replaced for the bluray player, and HDMI port for the rear entertainment.
Apart from that, I know the blind spot monitoring system was changed for the 2013 year and newer. They deleted the blind spot module which would communicate with each sensor and then transmit the data through the data lines, and made it so that each blind spot sensor became a module and communicated directly through the data lines system. I'm not sure how good this new system is compared to the older version.
It's entirely up to you what you'd like to do, and also luck. Just make sure it was taken care of by the previous owner and runs sounds and feels good. I'm on a budget so I'd buy the oldest vehicle in best shape. Prices are higher then ever right now too!