Buy for Great Software Support
The 2018 iPad ships with iOS 11.3 on board and it will get a software updates for a very long time. Apple typically delivers software support for several years and this updated model will get it for at least one year longer than the model it replaced.
Not only do you get great software today, including full support for augmented reality and all the cool new iOS 11 and iOS 11.3 features, but you will get the best experience on iOS 12 later this year when Apple delivers the next major upgrade.
While Apple often limits features on older devices, this iPad is new enough that we can expect almost all of the new iOS 12 features to come this year and for it to get a good deal of new features in future iOS updates as well.