LG fixed the G6 spec fragmentation with the G6 Plus. Granted it costs a bit more, but at least they saw some sense eventually.
Benchmarks....meh, battery will last me a full day most of the time, dash charge is better than Samsung's fast charge (old QC2 standard) by a mile when the phone is in use (handy in the car) and better/faster in general, never had IPX on any of my previous phones so not fussed with that, no sd slot i'll give you that but 128 vs 64GB of fast storage and dual sim which is always handy.
Advanced features? Samsung can't even get the basics right. That FPS location is a joke, single camera albeit a good one, 4GB ram, runs on old software and personally I prefer a flat screen to curved.
Stock android over anything, enough RAM that you never need to think about apps getting kicked from memory, a stock ROM build that has custom rom like custom features, class leading FPS, dual cams, runs the latest version of Android. Metal back vs glass, much less of a fingerprint mess and more durable. There's no other phone available that ticks all the boxes that the OP5 does. I'm just happy there's plenty of choice out there for everyone, and the S8 is a great phone with a lovely design no doubt, but it's beauty isn't enough to win me over. A phone for me is a tool first and foremost and the OP5 fits my bill better.
Really? Nitpicking over HDR. Yet the S8 doesn't even get FPS right, has 4GB RAM and runs an old build of Android.
G6 is LCD, S8 is curved. Neither is perfect. I'd rather have a 16:9 flat OLED.
The OP5 will be OP's best selling phone to date. There's no shortage of buyers.
You mention old software a lot, yet the OP5 isn't running 7.1.2, therefore it's also running "old" software. Will it get Android O? I'd hazard to guess that around the time it does, it will also be out on the S8/G6 etc. Hell I bet LG and Sony get Android O updates out before anyone else.
As for HDR, I didn't just mention the screen pluses for HDR alone, HDR means the screen is brighter as it has to comply with the requirements for it to be certified for HDR. The byproduct of this is greater usability in brighter conditions outdoors.
Whilst you remark about the 4GB RAM on the S8, I can remark about the limited storage capacity on the OP5, we could rally for days here! Truth be told, the 4GB RAM is utilised extremely well on the S8 anyway as countless youtube videos have shown. Apps and games resume from their previous position time after time.
Every OP phone has nearly been their best selling phone, but that phase is short, and better phones always steal away interest. It's as people have already mentioned, the OP5 is a bit too bland. Yes it's an upgrade over the 3T in some respects (camera, battery, design...), but it's still a design that's quickly fading into last gen territory. Phones like the Essential will be bringing unique design and features that seem to be more appealing.
The G6 display may also be LCD only, but it's a very very good LCD display, and because it supports HDR standard, it has to adhere to certain white and black levels. It's not as vibrant as AMOLED, but it's certainly very good. The OP5 still uses an old generation AMOLED panel.
This is a phone that should be up to £100 cheaper at launch. At that price point it would be a great phone for the price. But this is par for the course with "flagships" these days I suppose.