I have only had two (Nexus 6P and Galaxy S8+).
I'm conflicted because I like both. One important thing for me is the camera, and both have really good cameras. The 6P's HDR+ made some really beautiful photos in some cases, and the HDR on the S8+ is not so good, but I can take RAW photos which are fun to develop using the stock camera, which my 6P did not do.
The fingerprint sensor is definitely much more comfortable in the 6P. With the S8+, my hands are tiny, and when I reach it I end up smudging my camera all the time, which I hate. I have set up the eye recognition, but I just don't use it, I forget it's there, and am more used to the fingerprint sensor.
The S8+ has a more beautiful screen but it gets in the way when you are trying to type. I find myself typing letters that are to the edges of the screen accidentally all the time. This wasn't an issue on the 6P at all.
So... yup, I'm conflicted ^-^ haha. I think the S8+ has more interesting features and vendor apps than the 6P (the stock text recognition thing app has helped me tons), but sometimes, I wish my 6P didn't die on me.