The pricing is close, but unlike the Necron forces, these two sets serve a different purpose on the battlefield..
The 2016 set is more tactical - the Raider transport and Kabalite Warriors serve the swift interdiction and ranged warfare with the Reavers (amazing models!) providing speedy assault and an Archon to be all buff and kick some arse .
The 2018 set on the other handy is all about assault - Wyches for vicious hand to hand, the Venom for fast light transport and support and the venerable Reavers for zooming across the board and killing things! Then there's the Succubus, an amazing model with some serious speed and killing power. Not to everyone's taste, but not to be sniffed at either.
In reality, the Drukhari could have both these boxes existing at the same time - they serve different purposes and certainly don't cannibalize each other apart from the Reavers, and from what GW are saying, the Reavers are getting some love this time around. GW are also saying that the units in the 2018 set "feature a range of units that have been greatly improved" - so maybe this is a showcase set, a set someone can start with an actually win with.
Really in essence, unlike our Necron overview, this one is going to have to be inconclusive - with similar savings and the different roles each set specialises in, each set is really dependent on how you play.
The 2016 set feels like a core unit builder, while the 2018 feels like a more special forces builder.
The 2016 is more ranged while the 2018 is more assault and both have Reavers in support so you won't lose out there.
If the 2016 had the option to build a Ravager instead of just the standard Raider, then that would probably tip the scales for the 2016 as it gives the option to turn your transport/ support unit into a dedicated tank!.
If you like the 2016 though, you've only got a week to pick it up before it's gone!