Agree with the above poster – if you ride a newer bike and it didn’t do anything better then why not tart up your’s a bit with some bling bits. 2015 isn’t too long ago and it’ll still presumably have reasonably modern standards. Also if you get it painted then you’ll have something a bit unique to you.
What did you ride that you didn’t think was any better?
The main things that have probably changed are boost / metric shocks / bigger negative spring forks / longerer slackerer geometry since then.
Boost and metric aren’t a game changer imo – but the geo and better suspension units probably are incrementally better if it suits you. There is the danger that too long and slack actually can take some of the fun out of certain trails unless you really bomb down them.