Everything has changed, including the phone. I got an iPhone 6 a few weeks ago, and I am extremely happy to be back on iOS. I like my phone more than I ever liked my HTC One, and I'm more productive than ever.
Photos - I like the new Photos app quite a bit. Some have lamented the loss of the camera roll, but having all my photos together is great for how I use my phone. I really just can't wait for Photos to come to the Mac and I could be in heaven.
Day One - There is a great review of this app by Josh Ginter that you should definitely check out if you don't think you want this app. Journalling has never been one of my favorite things, but Day One has turned me into an avid journaller.
Camera - I like having all camera modes in the same app (photo, video, slow-mo, panorama) and with iOS 8, the advanced editing tools from apps like Camera+ and Afterlight are integrated into this app, so it's basically the best of all worlds.
App Store - I'm still in the honeymoon phase of owning an iPhone, so I'm downloading new apps all the time. It will eventually be demoted to another page, but I still use it daily.
Health - I'm using UP by Jawbone to track my steps, since FitBit apparently has no interest in integrating with HealthKit. The UP app tracks my activity and sleep and logs it into the Health app. I'm also manually logging my weight in Health until Withings gets their app to work with HealthKit[^1].
Mail - Crazy, I know, but no other email app I have tried is as reliable at fetching my email, works with Gmail and Fastmail, and has a quick interface for triaging my inbox. It makes no sense to me why extensions are not supported in Mail, though. Why can't I forward an email to my Things todo list or save a ling in a message to Pinboard? Madness!
Transmit - This FTP app is how I run my blog mostly from my phone. Transmit has an excellent extension that lets me upload new posts to my blog in just a few seconds, and from any app. It also lets me fix anything on the site, which I showed off in this video. Transmit also integrates with your Amazon S3 storage, so I can upload or download anything I want to share online.
Clock - Mostly for setting my alarm at night. Exciting, I know. ;)
Dark Sky - Temperature is not as important to me as whether it's going to rain/snow today. With extremely reliable forecasts that project when precipitation will hit your exact spot down to the minute, Dark Sky is the app I go to when I look out the window and ask, "does that look like rain?"
Paper - I find Paper to be a much more enjoyable way to browse Facebook than their official app. Everything looks better, and I love that the interface places all content at the bottom of the screen, which is perfect for the larger-screened iPhone 6.
Evernote - The best app for saving everthing. I don't use it for everything, but it's nice to know it's there when I have some random thing I need to keep for later.
YouTube - Because your phone doesn't always have to be about getting stuff done.
iA Writer Pro - I used to write in Editorial, but now with the help of Transmit's extension, I can write in this beautiful app and upload to my server all in one place. It's pricy, but worth it for me.
Ello - Yup, I still use Ello everyday. They don't have an iOS app yet, which stinks because the web app isn't great. Still, I keep it here because I don't have a choice.
TapCellar - I added this just yesterday, and it's not quite what I was expecting. I'm not sure it's for me, and I'm a bit shocked that it doesn't have compatibility with the iPhone 6 screen size. A review will be coming soon.
Maps - I gotta get around, and Maps gets the job done. My favorite thing is that it takes over the lock screen when in navigation mode.
Unread - A beautiful app that makes reading the news a delight.
Pocket Casts - You have a bunch of choices for how you listen to your podcasts, and your choice ultimately comes down to your personal preference, but Pocket Casts continues to be my pick. Overcast would be my second choice, but I can't find a good enough reason to switch away from something that makes me happy.
Google Play Music - I'm shocked that in a world where I can use Spotify, Rdio, iTunes Match, Beats, Rhapsody, and many other services to listen to the world's music, Google actually has the best option. I love that the app shows me my most recent additions to my library, suggested artists, and smart playlists all when I first launch the app. Those are exactly what I usually want to listen to anyway, and it's the only app that shows them to me so well.
Messages - Yup.
Tweetbot - There simply is no better app for browsing Twitter on any platform.
Drafts - When I just need to save something quickly, this is what I use. Evernote is for things I never want to lose, Drafts is for things I just need now.
Safari - Better than Chrome in 2 important ways. One, it's faster, which is huge on a mobile browser. Two, it supports extensions, which Chrome does not.
[^1]: It supposedly already does, but I can't get it to work at all.