I think my list is a little different to those above so to add to the options;
QuickPlan Pro - this has changed how I plan the business and saves me about an hour a week, what a god send. Simple(ish) Gaant planning software. Haven't figured out whether it can tell me if I over allocate resources on a certain day yet, if it gets that clever I'll be really happy!
Tableau - The mobile version of the Desktop Reader which ties all my graphs, stats and data together and keeps me knowing whether we're making money
Vizable - on the road intuitive graph maker from Tableau, great for a quick 'throw together' of simpler data sets and a really intuitive way of looking through data and information in graphical form. My go to spot now rather than PivotTables (for data too simple to need Tableau itself)
TeamViewer - Remote Control of my Desktop when I'm away from home but suddenly find I didn't back a file up to Dropbox or I need a OS X only app (that list is getting shorter and shorter)
Printer Pro - From Readdle, easily handle printing anything to any printer... just so long as it's connected to my desktop

Needs a Black and White option and it'll be even better.
WebEx - For web conferencing and meetings incl sharing files or viewing other peoples desktops/presentations
Outlook - Because email should be this simple (The advantage of a swipe for archive and a swipe for delete makes my aim of 0 email in the inbox so much easier with less emails sitting in "All Mail" as I now file nothing things are still relative easy to find)
OneNote - Just because I can see the tabs up the top and down the side, flicking between 'pads' is so much easier. I miss not being able to lasso and move things around the screen but the flicking about is so good I've foregone that cut and move feature of Notability and Goodnotes.
Security Camera - Software App for monitoring our security systems around the country. The bigger screen means seeing what's going on is properly possible.
Speedtest - Because doing a quick speed check when I'm visiting one of our 20 sites across the country if they're saying the net is slow becomes so much easier (also on my phone)
And yes... MS Office and Dropbox.
And then... Crossy Road, because we all need a 5 minute break sometimes.
Most wished for App/Feature: True offline mode on Dropbox - edit a file from Dropbox in Excel, save it back to Dropbox when I have no connection and Dropbox uploads/syncs back to itself next time I'm connected.
2nd Most wished for: Excel to be able to unlock workbooks/sheets. I'm going to have to make a decision at some point just how much I want our team to be able to break our spreadsheets for the sake of me being able to edit them from on the iPad :-/