Android has become so good so that it doesn't really matter anymore if you are running the absolute latest OS version. Since at least Android 6.0 the OS is very stable and reliable.
So the reason to buy a pure Android phone, like the Nexus or Pixel phones, is not so strong anymore. You can easily buy any modern phone from, for example, Huawei, LG or Samsung that runs at least Android 6.0 or higher, and still enjoy a very reliable, feature-rich and safe OS.
All modern and popular phones often get updated at least once a year, and personally I think that's perfectly fine.
So when I bought my Nexus 6P last year, I did it just because I wanted to try pure android and using my phone "The Google Way". And I admit, it's a great experience. But I am sure that both the LG G6 and Samsung Galaxy S8 this year will have a very enjoyable experience too. And you can run "The Google Way" on these phones too. All the Google services and apps are available if you want, so it's quite easy to use, only Google services if that's what you want.
And both LG's and Samsung's skins above Android has become much better and lighter for the eyes in the newest versions. So that is not a problem anymore either. But if you absolutely have to use Android as clean and pure as possible, you can always install your favorite launcher instead of the manufacturers own launcher that comes pre-installed. Then you can have your experience as you want it, and very near "Pure Android".
So by having a phone that runs Android 6.0 or above with its own skin above, is not such a huge problem anymore.
So I think I have decided to try Samsung again this year, by getting the Samsung Galaxy S8 Plus. I love the rumor about having a 6.2-inch display!