Pretty Hard decision at the Moment...
I own a Lumia 930 and I have an iPad Mini 2 - Ok it?s a phone and a tablet, so I only have the comparison concerning Software... The UI of iOS is just SOOOOOOO old School, no matter how often they add "Magical Colors, Scrolling of whatever"... Just a Bunch of Icons (JABOI?

) and that?s it... OK, I can arrange them how I want and put the into folders... hoooray...

. I?d definitely prefer WP in that case.. Live-Tiles that I can arrange how I want in size and position and it still is a clean and straight forward design...
But I agree that Apps are still a big Problem... not for the average User I guess (as long as they don?t want Snapchat, but don?t really see that as a must have

), but the platform is still either ignored or not really fully supported by many developers...
Just one Example: As a Photographer I can wirelessly connect my camera, copy the Pictures to the iPAD (would work with iPhone as well), import them into Lightrooom mobile, start editing, mark the best ones etc - and sync these editing settings with the PC via the Adobe Cloud. All that directly on location while drinking a beer and enjoying the Alps Panorama View - It just works and is pretty cool...
On Windows Phone: No Lightrooom Mobile, no official Olympus App (at least a 3rd Party one, but it obviously is not as good as the original one) nothing even annouced here. Same with Software like "Photographer's Ephemeris (TPE)", Triggertrap or any Smartphone enabled Photographers tool (Timelapse - Astro, Michron or similar Controllers for HighSpeed and Timelapse Photography)... Zero
I think Photography is not the only Area where they are way behind on Apps... But from a developers Point of view it?s understandable... Not many Users compared to other platforms, so why develop... And without the right Apps, it?s hard to gain more Marketshare... :-(
And if you want to use Microsoft Office, OneNote, Onedrive, Skype, Lync, Sway etc. - That?s available on Android and iOS as well...
I?ll wait fot the new W10M Devices and the final Windows 10 Mobile, before I decide which plattform will be next - and I really hope that it will get better concerning Apps...