I don't know if this is the best place to ask for unbiased answers as I haven't really followed this thread at all, but I have an iPhone 4S and am going to upgrade to either the iPhone 6 or Xperia Z3 Compact.
I know the Z3 has better battery life, storage and is waterproof. It is also less expensive, though by how much in Canada remains to be seen. I have a PS4 so remote play could be cool, but I also have a Vita and a 3DS. On the iPhone 6 side, I really like having the continuity between my phone and my Mac, iMessage and Find my iPhone with the family's phones. The fingerprint scanner seems like a nice touch too. I don't really know anything about how well NFC payments will be supported in Canada but that could be cool I guess, though on the mobile payment front we're so far behind countries like Japan that I'm not really focusing on that right now. I also have an AppleTV, but nowadays I mostly stream movies from my Mac, I don't mirror my iPhone much. I also have a PS3 and 360 so DLNA works on that front. Now here's the rest of the things I'm considering during this decision:
Durability (reviews seem inconsistent on which will better survive a drop test)
Camera (photo and video)
Display
Resale value
2 years worth of support (OS updates, etc.)
App Support
Performance (haven't found benchmarks comparing the two yet)
Which of these are in favour of one or the other?
I've pretty much been in the same boat as you, having had an iPhone as my daily driver for five years and switched to a Z3C last week. I'm happy with my decision, but I had been using an Android tablet full time for last few years so there wasn't too much of a culture shock.
But on some of your specific questions -
I'm using 1Password for password management, but I miss Touch ID and I think it's something Google really needs to up their game on. Password Management isn't as robust as it's become with iOS8 extensions either.
I really don't think Apple Pay will even launch outside the US in the next two years, so I think it's a non-issue. Non-US countries don't have the rampant security problems the US does with credit card processing so there's much less incentive for banks to co-operate and prioritise it.
I suspect the Z3C is significantly more robust, but the lack of Sony Stores with servicing will make it a lot harder to get it fixed if you do kill it. I'd get a protector or a case for the rear glass though.
I think the Chromecast shits all over Apple TV as a mirroring solution, even when you're running iOS TBH.
The camera is as good as the one on my iPhone 5 certainly, in every area except for focus speed and reliability, which is worse. It's not a crippling problem, but it's not ideal. As a counter, a dedicated hardware camera button is great and something I've said iOS needed for some time, and the front facing camera is better than the one on my iPhone 5.
The Z3C does need a bit of work out of the box - I needed to replace the launcher, and there's a bunch of cruft to delete and disable (but by and large you can get rid of it).
You can replace a fair amount of what Continuity does with Pushbullet, though annoyingly there's no native Mac client yet.
The display is pretty comparable to the iPhone 5 IMO, but the battery life shits all over it. I never tried a 6 to see if it'd be better in practice.
I never used iMessage on iOS as SMSes are effectively free outside of North America and iMessage is a terrible protocol, so I can't tell you if you'll miss it. Likewise "Find my Friends." I'm sure there will be some Android equivalent, but it might not be what your friends use.
Also, is there voice-command to set up an alarm clock? Because almost every night I go "Wake up me up at __ a.m.". I'm pretty sure there is, but just in case.
Yup, you just tell Google Now to do it.
