I thought I'd add my top 5 into the mix, although I've probably missed the deadline :)
1 - Test Explorer
|Test Explorer, Docked Left in my Main Window|
I really love having Test Explorer baked in, especially when the XUnit runner is installed. Previously I used to use ReSharper's test manager but now I pretty much only use this. The addition of playlists in VS2013 has also helped.
You can run tests automatically after build, search your tests and group in various ways. One of my most used features.
2 - Navigate To or as I say Ctrl + T
|Finding those Test Types are now just one Key Combo away :)|
This is another feature I used to use Resharper extensively for, the ability to quickly find a type by name. Just hit Ctrl+, start typing, instant win :)
3 - Server Explorer with Azure Integration
|Managing and Viewing Azure Services is now simple|
As much as I love this feature it does have a few issues, for me it seems to constantly forget my login details, so if I happen to have VS crash or have rebooted I have to re login, as my account uses 2-Step Authentication (Which everyone's should ;)) it's a bit of a faff.
4 - Editor Extensions
|If only VS could do this.... Oh look an extension...|
This may seem like an odd feature to include but I think having Extensions within Visual Studio is a game changer. You have always had the ability to install IDE extensions, Resharper etc however they were always "drawn on top" or didn't feel quite native. Now that the IDE has been redesigned to be fully extensible, the editors. test explorer etc, your experience can be greatly enhanced by some simple extension that is fully integrated.
Personally I wouldn't be without Web Essentials, Productivity Power Tools, Chutzpah, XUnit Runner
I even know friends and colleagues who write extensions just to make their lives easier.
5 - Full VS Colour Schemes
|Which theme do I use today...|
I debated adding this to my list, I know other's have said Intellisense, IntelliTrace etc which are great features however I think its often underestimated the effect changing the VS Theme has.
I've always changed my editor area theme from the default to often something dark, I've blogged about this before, but now having the full IDE change really reduces the clashes and I think looks better and improves the overall integrated feel. I loved blend having the dark theme so now VS has I'm happy ;)
Depending on how I'm feeling, and more often how my eyes are feeling I sometimes switch between blue and dark.
And there we are 5 of my favourite Visual Studio IDE features :)