They all have good and bad points, 15-16 will be collector items as they were the beginning, try and find a 1969 H1 and if you do you will pay big bucks for an original.
There is no known systemic faults with the H2, most problems have been mods along with abuse outside the H2's reliability envelope. Although when it happens they complain the biggest failure is to look in the mirror. Example, one owner complained about gearbox failure and KHI would not replace the unit for free, really complained with threats of exposing how badly the gearbox was built to everybody on the internet. His problem was his voice was an exact match to somebody who YouTubes his mods. So don't listen to this, the bike is built real well.
And another thing, don't fall into the trap of people comparing the H2 to another make as the fastest motorcycle in the world, it is not! It is though the fastest accelerating production motorcycle in the world. So keep that in mind when the Ducati, BMW or any other owner tries to talk you down, they cant.