So, I just requested a refund for my 5X, and I'll tell you why in a tl;dr. It's basically the 5 with more problems.
Non tl;dr:
What problems?
Well, the battery life is just as bad as a veteran 5 out of the box. Battery life lasted 10 hours with a full charge while moderately using it. USB Type C is a great standard, but isn't anywhere near as implemented when Micro/Mini were introduced. Type A at the time was globally used, and piggybacking off Type A start plug to a mini/micro end helped the transition. Pushing for both sides Type C with motherboard specs not even including Type C until Q1 2016 isn't how to go about implementing it. (More USB woes) Using a Type A -> Type C cable doesn't work properly. I get mixed results with it. First time I tried it on my Windows 8.1 box with a USB 3.0 Type A connector, the driver it installed was wrong, I had to look up how to get it to discover the 5X properly, then when it finally did, I couldn't find the option to set it in to MTP mode because it defaults in to Charge Only mode. It was in the swipe down menu. Elapsed time to figure out: 30 minutes. I had forgotten about it later at a friend's house when I needed to use the phone as a storage device, again had to figure out the driver/MTP shit. Elapsed time again with just remembering how to do the driver crap: 15 minutes. You could say shame on me for forgetting it the first time, but it's like, why would I look in the swipe down menu with no notification showing? The 5 showed a "USB modes available" notification thing that would show up on the lock screen that I would double tap and it would bring up options. The 5X doesn't do that. My first instinct to get it in to MTP mode would be go to settings and set something in the USB sub menu. But if you google for help with the 5X, it just finds results for the 5, because that's what people click on... When I used the conversion cable on the USB plug for my 2013 Carolla, it doesn't work at all, and when I use it on my Laptop with USB 1.1, it only allows for charging. The signal on the thing was trash compared to iPhones around me. My dad would have 1-2 bars on his 6 Plus, and I would have 0 bars, holding the fucking thing up some retard from the 90s trying to find a signal. I almost looked for an antenna to pull up... However this only happened in a sports bar we were in once, and hasn't happened again. Still pissed me off that it happened at all.
Here's the log I had with the Google Support team.
I'm still impressed with the professionalism Google provides with all their products, even if they aren't produced or designed by Google directly.
I will be going back to my 5, even though it literally requires life support to function, being plugged in constantly. That isn't a problem with everything around me having a Type A plug.
Have you checked out the HTC One A9? I just ordered one. Really good reviews from PocketNow, Android Authority, and the Verge. I was comparing between the 5X and the A9 as they are roughly the same price (for the next few days until the A9 increases in price for some stupid reason). The battery is smaller, but HTC is known for good battery life, and all the reviews I saw said it was lasting all day. Also, it's thin enough and doesn't have the fingerprint scanner on the back, so you could put a case with an external battery. Also QuickCharge 3.0. Also micro SD.
I think you should get the nexus 6, not the 6p the older 6 with the marshmallow update i get 2-3 days of usage, granted my usages is checking the time, checking a few text checking facebook and a few emails. so with other people's usages probably a day and a half. I have service everywhere i go (us cellular). and it has quick charge and holy shit is it quick. like from 15% to 90% in like 20 minutes.
If you are worried about the size, I have small/medium sized hands and i don't feel like i am going to drop it, the cuved back helps with the natural way you grip things. I will say that it is a two handed phone. after using it for some time now i was handed a S5 and if felt like an ipod nano.
If their motivation is budget, two of those phones don't work. If their motivation is size three of those phones don't work. If their motivation is fast-charging, two of those options don't succeed. Those are all great phones, but I don't think they fit the criteria.
Ha! I was wondering when the reviews would start trickling in on Hammerhead 2.0. I got a developers model last year and didnt even complete the benchmark before throwing it back in the return box. But for users returning to nex5, my two cents, if you want to see the true power of this device you need to de-google it. (no framework, no gapps)
As you titled your post these sound like your subjective woes. Either you had services in the background - unknown to you - draining battery or this was a manufacturing flaw.
If I may aswell, from your Google chat log you don't seem incredibly technologically oriented. Expecting a support email to arrive within 60 seconds is not very realistic. So too there may have simply been background apps and services running (that you never unchecked) on data contributing to your quick battery drain.