OK - since you insist:
You responded to my list of actual things that SP can't do that iOS can as 'user preference.' Sorry. That doesn't get you very far. Especially when the favorite defense here is to point out all the things the iPad can't do that the Surface can.
The answer has been given many, many times..
The Surface cannot stream music to a Bluetooth or wireless music system without changing power settings which then consume a considerable amount of power to do this simple task.
1. Jeff already pointed out Xbox does it (you dismissively respond it's an application no one uses - kind of an "iPaddy" response)>
2. For you this may be critical - for most, how often is this even important, much less an issue.
If I want email with a notification system, I have to use the awful Mail app. I use Microsoft's own Outlook on iOS because it is so good on that platform. Where is it in the Windows store?
1. Outlook (Accompli) is coming shortly.
2. Many of us just use that "awful" desktop version of Outlook even though it is "only" a tablet.
There are no decent chat apps, that again, have a good notification system. On iOS I have access to both Google Hangouts and iMessage which means I can send or receive messages - text, video, photo, whatever, from any of those devices, respond via whatever is in hand at the moment.
Absence of Hangouts and iMessage is proprietary behavior of Google and Apple - not Microsoft's fault. You can't get iMessage anywhere except Apple hardware, so same complaint applies to ANY Android tablet - does that make all Android tablets inferior/mediocre.
A number of magazines and newspapers are not available at all on Windows. The majority of the ones that are have apps that are 3 years or more behind their counterparts on iOS.
I find Next Issue to be great on my SPro3 - ever give it a try? Again, show me where your go to magazines are available on iOS and Android, and not on Windows...
Sending video content to a 2nd screen via Miracast is decidedly clunky. It works great if all you want to do is mirror your screen. Less well if you want to interact with the video that is playing on that screen. On iOS this works flawlessly and the controls are always intuitively available from the iOS device with no weirdness. It's consistent and reliable.
It's flawless on iOS IF paired to Apple TV - good luck on other protocols (kind of like complaining that iMessage doesn't work on Android or Windows tablets).
Battery life. I am extremely careful about what I have open when I use the SP as a tablet, have switched to IE, etc. yet my battery life cycles between ~4-7 hours. My iPad consistently goes 12 hours, often 20. I charge it once a week. If it has 10% battery left, I know that will last me at least another hour and a half of normal use.
I'll give you that one, in part, BUT I've never gotten less than 6-7 hours of productivity, websurfing, and WiFi on my SPro 3 - but then again I'm running a Core i5 Intel processor and not a tablet only, app running only, chipset.
Camera quality. We use our iPads to video chat every day. The cameras on the Surface are terrible indoors in the evening. Worse than iPads now 4 generations old.
There are apps that are just better than their websites. This definitely applies to Facebook, Twitter, any music streaming site, etc. On Twitter, especially, many sites give you access to their articles through the iOS app links, but not through the website interface or the (terrible) Windows apps.
Again, absence of Facebook, Twitter, streaming, iOS links is again proprietary behavior of Apple and it's slavishly devoted developers, NOT a fundamental fault of Microsoft or it's tablet ability. "Apps" are generally better than website interface BECAUSE it is singular focus - but then do you really want to deal with a separate "app" for every website? Really?
Password managers. Try logging in to your password manager on the Surface without the keyboard attached. On my iPad it takes the touch of a finger and I'm in, or logged in to any compatible app or website. On the Surface I have to navigate a desktop app that doesn't respond well to touch, and type out my 15+ character password on the on-screen keyboard.
Are you touting touch ID here (I love it on my iPhone 6 Plus) - if so this is TRULY a red herring because it only became available with iPad Air 2 - AND SINCE NO ANDROID HAS IT EITHER, then ALL tablets are inferior.
These are just a few of the things that apply mostly to me. Other users could add to this list 10 fold. The Surface is a nice lightweight laptop. It's a great note-taking device with a great digitizer. It's a mediocre tablet.
By your own list above, EVERY tablet, whatever operating system or manufacturer, is mediocre to your iPad Air 2...I'm sure Apple would agree but obviously the rest of the world does not.
The thing about an iPad is that it can begin to fill a space in your life where previously there was no computer that fit there. It's not intended to be a replacement for a laptop or desktop. It's intended to be much better than those devices at a lot of the things people use computing devices for today. And that's why they've sold 250 million of them in less than 5 years.
Only true BEFORE Surface Pro 3 was released. The SPro 3 not only fulfills your needs for a real computer, it more than adequately (I say excellently) fills those other spaces. Face fact friend, until Jobs declared that we must have the third standard (between smartphone and laptop/desktop) none of us even KNEW those unfulfilled spaces exited. In reality, they didn't exist - he just did a masterful job of making it easier to do all of the same things we did with smartphones/laptop with his "tweener" device - the iPad. That in itself was a great achievement, but no better than the inventor of the cordless drill to use what the big powered corded drills did before it.
I'm not denegrating Jobs or Apple - I struggled with "convertible" Windows devices for note taking for years, and without iPad we would have NEVER had Surface Pro 3 - thank you Apple for that competitive punch in the face - but please, all of you fanboys, quit declaring the SPro 3 is a mediocre/inferior tablet, because by your very standards ALL tablets without a fruit engraved on the back are mediocre/inferior