[OnePlus 6 Guides, News, & Discussion] n2851991m:
I used the S8(Exynos 4GB + 64GB + 128GB SD Card) for about a year before moving to the OP6(8GB + 128 GB), I do love the OP6 but there are a few things I miss about the S8.

The Good :

Super fast : The OP6 leaves the S8 miles behind in terms of sheer speed and performance. (I regularly get those 5 extra kills in PUBG mobile on the OP6)

Ram Management : Again I sometimes dont even know how many apps I have running and I can switch to any of them and they remain in memory for days. If I was an app, I believe even I would fit in that memory with room to spare.

Battery Life : I never ever need to worry about my phone running out of Juice unexpectedly, On my S8 Id take it off charge at 11AM and it would be down to 30% by 3PM because I decided to watch a movie.

First and Third Party accessories : I had a first party TPG available for purchase on day 1 for the OP6. There are no TPG's available for the S8 and the plastic nonsense is super expensive and always has an orange peel effect that spoils the beautiful display.

Game Mode : Samsung, You need to outright copy the game mode from the OP6, Don't even bother touching it.

Dash Charge : Enough Said.

Custom Rom and community support : Just take a look at the forums for the OP6 and the S8. On the OP6 we have such a large active community that are already building new kernels, modded roms, tools and so much more. The S8 forums only have people bickering over when the next monthly patch will be available and how their devices slow down after each update.

Software Updates : we all know that Samsung is a pile of turds when it comes to updates. On the OP6 I have received 3 software updates already in the 2 weeks I have this phone. Though there are a few niggles here and there, the software is pretty stable. And looking at this community, I know we will have support for this phone for the next 2+ years atleast. On Samsung, I had to resort to factory resetting the phone every month to get the phone performing as best as it could, but that came at the cost of serious battery life issues.

The Bad :

The Camera : In auto mode, the OP6 does click better pictures than the S8, But I personally always use the manual mode when I have the time. The Manual Mode on the S8 is light years ahead of what we get on the OP6. Yes the controls are the same, Exposure, ISO, White Balance etc. But the single camera S8 still clicks better pics on manual mode than any other phone (With the exception of the S9 or the Note 8)

Video Enhancer : I really loved this feature. Watching movies on the phone was utter joy. First movie I watched on the OP6, I kept noticing how "washed out" the screen looked (This is only comparing the video enhancer)

IP68 : The first week after I bought the S8, I went on a trek in Monsoon conditions, Obviously the S8 shrugged it off like it was a small spray. Then I took the phone into a waterfall. Same result. The phone only game me a warning to not charge it until it is completely dry. On the OP6 I am not so confident. I guess only time will tell.

The Bixby Button : Wait! hold on.

Don't get me wrong. I remapped the button and disabled bixby on day 1. The OP6 does have an alert slider that is immensely useful, But with a simple app and some adb magic. The bixby button was remapped to launch the Google Assistant. With the new gesture navigation on the OP6(That I absolutely love), There is no way to launch the google assistant other than saying OK Google, which is not always possible. I would have loved a remappable app button on this phone.

*Minor Edits*