I got back to my Galaxy Note (first version) for fun with a brand new ROM... And I think i'm not going back to my Lumia 920 :)
Applications & Marketplace
As you know, the Windows Phone 8 ecosystem is currently very poors, there isn't many applciations as there is on Android, and the ones that exists are not features as the Android one or buggy (Yes, Spotify !)Also, the feature that allows you to remotely install an application from your computer using the marketplace web interface don't work 90% of the time.
IT Tools
This is simple, there is just nothing for IT on Windows Phone...Where are the VPNs ?
Where are the tools from Cisco ? (Community forum application etc.)
Xbox Music vs Spotify
Xbox Music is great on Windows phone, but only on this platform.The Xbox Music applications on other platforms are terrible (Windows 8...), and they don't even exists for other OS or older versions of Windows, this is just unacceptable (What if I want to listen to my music at work on my W7 computer ?).
Skydrive vs Google Drive
Skydrive is clearly not at the level of Google Drive or Dropbox.Speeds are slow at both downloading and uploading, there is not versioning and the client application on Windows is kinda buggy, I have a lot of crash with it and many issue when I have to restart it for it to continue to sync.
Never had this kind of issue with Dropbox and Google Drive
Office 365 vs Google Apps
Okay.... Microsoft... The last update of Office 365 for Offic 2013 is just horrible. The administration interface has just lost 90% of it's features, you can't even set users group or aliases from the web interface and have to go into Powershell to do this !Even the (ex)Free Google Apps plan does better !
Tethering
The tethering on my Lumia has never worked, it always drop the wifi connection between my laptop and my mobile phone...Why don't WP8 supports others type of tethering like Bluetooth and USB ?
Openness
That's it, I love to flash my phone using different roms to have a system that is made for me !What I will miss
Unified user experience : Having everywhere the same interface guideline if great and very pleasant.Interface responsiness : No more to say... The Windows Phone interface never has slowdowns or freezes. Android is sluggish in comparison to Windows Phone
Camera : The purpose of lens is great, this allows you to extends the camera apps with great features (like manual focus, HDR, etc.). And of course the awesomeness of the Lumia 920 lens :)
Xbox Live: Well, this is personal but I really love my Xbox live avatar !
So, i'm back on Android ;)