And a brief description of some noteworthy apps on it...
Messages - With iMessage, my iPad is just another window into my text conversations. I use this app just as much on the iPad and Mac as I do on the phone.
Spark Mail - One of my favorite Mail app replacements. Spark has enough power features to merit its own blog post, but the feature I am finding quite useful right now is the ability to filter just the important notifications so I am not bothered by junk email throughout the day.
Notes - The Apple Notes app is increasingly becoming my go to for most of my note taking needs. I love using it for checklists, outlines, and sketching. The action extension (accessible from within any iOS app by pressing the square with the arrow pointing out of it) allows me to clip whatever I am looking at, no matter the app, into a new note or existing note.
OmniFocus - This app runs my life. I keep it on the dock for easy access to my tasks and projects.
Drafts - Most of what I type on the iPad starts here and then later gets filtered into the app that best suits its content. I am often sending drafts to Twitter, OmniFocus, Notes app, and my blog app.
Dropbox - Pretty much all of my documents live here. This is where I browse, edit, and share them from my iPad.
Documents - Think of Documents as the missing Finder app on iPad. It allows you to work with files locally on the iPad but also from various cloud services like Dropbox and Google Drive. In fact, it allows you to see all of your content from all of your cloud drives all in the same window. Right now this is crucial for me because I am using a personal and professional Google Drive account simultaneously. Documents allows me to be logged into both of them at the same time, something not even my Mac can do.
Pages - Of all the basic "office" style applications I work with, Pages is perhaps the most essential. Pages is a beautiful and intuitive replacement for Microsoft Word. I love how it seamlessly syncs my documents across all devices through iCloud Drive.
Byword - Byword is a plain text editor. If I am typing a document of length that doesn't need to look pretty or include any multimedia, I usually type it here. Byword has a clutter free atmosphere that allows me to focus on just the text I am typing rather than buttons and tools.
forScore - My entire mobile score workflow is based on this app. I pull scores from my Dropbox account right into forScore where I can annotate them, perform from them, categorize them, and add all sorts of interesting metadata to them.
Blog - This is the app I use to post to my blog on my Squarespace website.
Notion - Still the best music notation software on iPad. I use it for small projects and defer to Sibelius on my Mac still for larger scale work. Notion allows you to scribble on a staff with the Apple Pencil and then it converts your hand writing into crystal clear notation. It's magical.
Google Drive - I have been deviating a little bit from my entirely Dropbox based workflow recently, in part because some colleagues of mine prefer to use Google Drive for collaboration. I really like the Google Drive app. I just wish that the Google Docs and Sheets app took advantage of iPad Pro split screen multitasking.
Sheets - Of all the a Google Doc apps, Sheets is the one I use the most. There are a bunch of ways to use cloud drives to collaborate with others on spreadsheets but Google Sheets is the only one I trust to sync everyone's data reliably. I use this app very frequently to access docs related to scheduling and inventory.
GoodNotes - Although I am using Apple Notes for most things, I find that a few tasks require a little more power. GoodNotes is great at a couple of things. First of all, it has excellent Apple Pencil support for handwritten note taking and sketching. Next, I love how easy it is to combine my own notes along with other PDFs from my iPad all into the same notebooks. GoodNotes (and apps like Notability, which I was previously using until I started trying GN) does the best job allowing me to immediately scribble on top of PDFs. Many PDF annotation apps offer this feature but typically take a couple of taps to enter into annotation mode. GoodNotes feels more like a piece of paper. Also, while there are plenty of great dedicated score apps (including Notion from earlier in this post), I love that GN has a staff paper option. In fact, it is easy to intermingle a diverse range of paper styles all within the same notebook.
Slack - What is Slack? My favorite communication tool on the planet. Slack is an awesome collaboration tool for teams. I am not really sure this is the place to detail the range of its features, but I will share that the music team at my school has been using Slack for the past few months and it has been a real game changer. It is coming to replace both text messaging and email for us. The basic idea behind Slack is that a team can have multiple different "channels" within their team which are basically conversation threads. Any member of the team can be in any channel. For example, all of the people in our team who teach band or orchestra classes are part of an instrumental music channel where we have almost all of our digital communication about that subject. The choir guy doesn't have to see any of that conversation. There is a general channel for general communication and even a random channel so that my endless gifs do not annoy my coworkers by disrupting otherwise productive discussions. Slack takes the cruft and formality out of the picture, enabling simple text conversation while also empowering us to be way better organized about the way we collaborate on different projects. Slack also has tons of integrations with other services. For example, with the Google Drive integration, I can share Google Docs right from within a Slack channel and other users can comment on it or launch right into it.
1Password - My favorite app for managing passwords, software serial numbers, secure notes, and more. I never forget a password with this app. And Touch ID on my iPad allows me to log in anywhere by simply touching my thumb to the home button.
Scrivener - Scrivener is a non-linear writing tool. I used the Mac version to write my book. I am beginning to plan some other writing projects and am enjoying the ability to sync my projects from Mac to iPad and back again.
comiXology - I pretty much only have time to read comic books in the summer. If you are in to this sort of thing, Amazon's comiXology app is the place to buy and read your comics (actually, because Amazon likes to avoid paying Apple's 30 percent of every purchase, you will have to buy the comics from Amazon or comiXology's website). comiXology has this cool feature I like where it smartly detects the ends of the frames and allows you to scroll through each of them full screen. Right now, I am reading the Walking Dead series.
BusyCal - I am trying out this Calendar replacement right now. Usually, my calendar app of choice is Fantastical but BusyCal allows me to do some interesting things like, for example, associate contacts in my address book with events for better context.