Hello! Though I own an LG product (a G3), I would go for the 6P if I was in your position. Here are my reasonings:
- Nexus has a reputation of putting out quality products. Even if the 6P is somewhat "dated" now, Nexus still provides an experience that will make the phone last for you
--> one reason for that being that Nexus is the first to get software updates and so you'll never be left in the dark
- Nexus is stock Android and so you'll get the best of what Google has to offer with no bloatware
- the 6P has a sleek camera experience and though the G5 takes good photos, the 6P, IMO, would most likely give you a better bang for your buck in this department
- the 6P's screen/display is such that if you do Web browsing/media viewing, you will have a much better experience
- since it has been out for a while, the 6P will be at a good price now; and this will be even truer when its Nexus successors are released
I guess you didn't actually read the post since the OP stated that he is able to get both at the same price.
You also write as if the 6Ps screen is better for reasons that are not at all clear. Sure, it's bigger but not by much and that comes at the cost of it being not very easy to hold (I know because I own one). Then you can get into the AMOLED vs IPS debate and each have benefits and drawbacks. IPS doesn't suffer from atrocious colour shifting if you view it from a different angle while AMOLED displays can save power if you use black backgrounds or themes since it is not illuminating any pixels. The list goes on.
Also, what's a "sleek camera"? You completely ignore the fact that the G5 has this extra wide angle lens camera which, depending on the person using it can be a lot of fun as well as having manual controls natively rather than the uber simplistic Google Camera app.
That's not to say that the 6P takes worse images - it probably takes better ones most of the time if you use HDR+ but it's slow to process, takes longer to load up and it would be better if the sensor just had better dynamic range in the first place. You can't burst photo with HDR+, you can't take HDR+ video. It's not entirely practical even if the results are very good.
On top of that, there are things you mentioned that make me question if you are even able to recommend anything:
1. Google is the company that distributes Nexus devices, not "Nexus". Nexus is not a company.
2. The fact that there are so many devices not on the latest version of Android means that "the best of what Google has to offer" is available on pretty much every device running Lollipop and up. So with a 2016 flagship you're not left in the dark. Heck, even iPhones are great Google phones.
I have a 6P and I like it a lot but you're very clearly biased and are recommending something very blindly. That's not very helpful.