Oh damn, you must got a faulty one, or dunno. In everything you described it, i haven't experience things like that on my Lumia 950. It runs perfectly.
But to not confuse you, let me tell you my experience compared to yours.
- Set Up The Account
Well, I did set up my account right away, in a few seconds (well, ok it was a minute or two), no problem whatsoever. My contacts start to sync the moment I got it connected on my wi-fi.
- Connectivity
I connect it on my wi-fi network and on my mobile internet in the first attempt. 1-2 seconds and bam, you're connected.
- Restoring Settings
Settings on WP8.1 and W10Mobile are totally different. It's a different OS, dunno how you expected to be restored from WP8.1 to W10Mobile?
- Store Opening
If at that time your apps were updating in the background, of course the store will take a time to load. Otherwise it opens in a second, at least on my Lumia 950 opens in a second, unless there is some problem on the Microsoft side.
- Not Playing 1080p Videos
Have you tried other 3rd party Youtube clients? When i was on WP8.1 I use to use Tubecast, cuz it had design that i liked, but somehow it didn't work that well on W10Mobile as it worked on WP8.1. Then i download MyTube, oh boy, what a difference. It can play everything, try it.
- Loading...
Technically apps created for WP8.1 can work on Windows 10 Mobile but they won't work that nice as they work on WP8.1 mainly if they are created in Silverlight and not on UWP. Silverlight apps tend to have that Loading thing. UWP apps created especially for W10Mobile works perfectly on my phone, no loading, nothing.
- OS Running
Yeah, there are some hiccups here and there with the new OS, but those are minor, more than 95% of the OS works as it should be. 3GB of RAM is not a measure for sluggish performance of the OS. There are Android phones with 4 and more GB of RAM and you can still see sluggish work of the OS.
- OS Update
You said even after upgrade it to Creators update, the OS still works bad. Have you tried to hard (factory) reset the device after that? I did mine, and it works like a champ. A friend of mine did update his Lumia 640XL to Creators update and the OS was working very bad. Once we hard reset it, now it works flawlessly.
- The Phone Design
Well, it's not the prettiest, but you have lots of cases to change that. It doesn't look premium like 930, but I personally don't give a damn how the phone works. It's not my show-off item, it's my productivity tool. If it works for me, i don't care how it looks.
- The Screen
A 1080p AMOLED screen with a pixel density of 441ppi
can't look or be sharper than more advanced AMOLED panel with 2K display and pixel density of 564ppi, let's not exaggerate here.
Bottom line, dunno if you got new Lumia 950 or second hand or refurbished, but something is wrong with that device (hardware wise). I have my Lumia 950 since November 2016, and i love every bit of it, It works like a champion, the way i like it. I read so many people have various problems with their Lumias 950/950XL, but will you believe me if i told you that on my Lumia 950 I haven't occur any of those problems? Dunno, maybe i just got lucky and got a perfectly manufactured one, lol.
Look bro, I am not opposing your opinion, obviously you made your mind. But to be honest, a day or two with a new device is not enough to judge the performance od the one. I am just stating here my points of view about this device. Is by far the best device i ever held (yes i got an iPhone and high end Androids too), but this one works best for me.
Hope you won't understand me wrong
Cheers