Value to price ratio: 10/10
As a 6t user, I will address the points of critique:
1) I leave the adapter that came with the phone on my headphones. I only use my headphones and when I do, it is very infrequently. I reality, there have not been many situations where I needed to plug an auxiliary cord into my phone (considering my car has Bluetooth).
2) the fingerprint scanner is significantly faster than Samsung s10, and is shown to unlock faster than some iPhones with fingerprint readers (which also fail to work with wet fingers). It seems, the alternatives are not much better. Secondly, after some muscle memory you will be able to place your finger on the right spot just as fast as a fingerprint reader.
3) camera: quality is underrated and pretty good. Many comparisons to iPhone pixel and Samsung are available online, and in my opinion they do not have an significantly objective advantage. Especially in terms of reliability, 6t stock camera always works, and hasn't lagged for me while taking pictures. You can also get the gcam (Google cam) from xda which may be more pleasant to you, and you can take advantage of the portrait and night modes (also many comparisons online with the gcam on 6t). You have nothing to lose here, considering the gcam option.
4) wireless charging: do you own a wireless charger? I don't, and I don't feel the need to get one even if it was capable, due to amazing battery life, and charging speed (which OnePlus is faster than iPhone, Samsung & pixel... - see video comparisons online). And for those of you that do own wireless charger, please, share with us the speed at which they deliver charge, for those of us that are missing out..
5) IP rating: watch some videos of people doing water test (following the IP rating guidelines) on the 6t, you will be comforted. Watch "jerryrig -it -all" take apart the 6t and compare the sealings to IP rated Phones and you will be reassured. Also, phones with IP rating don't provide warranty coverage for water damage anyways. OnePlus saved you some bucks from going to the IP rating business.
Now for some pros:
Speed, with latest processor, and 6-8gb ram (in reality it's not about the amount, it's about the ram management, see online. This is something that among Android, OnePlus is actually doing great. There is a reason why iPhones work great with only 4gb ram).
Software: clean and smooth UI, latest updates (I'm not a beta user), customizable and useful features (I use night mode, and the flashlight gesture), no bloat ware or 3rd party apps.
Fast charging... Really fast.
Battery life, really great, at 3700mah (which in reality is an outcome of OnePlus optimized software, this phone does better than Samsung note 9 battery which much larger, due to lower screen resolution and software optimization i.e. less background processing) .
OLED FHD display, deep blacks, strong brightness, and color calibration options.
Phone service, works great, coverage and data speeds.
For USA, 6T only works on Att, TMobile (GSM networks) and Verizon. Not Sprint. I guess that a real con right there.