Chrome. 3 words: Integration, minimalism, speed.
All the google stuff works great through chrome, makes admin minimal, I have f*** all to hide XP
The clean, minimalistic look and fast, easy to use UI is for me the most stunning thing I have ever seen in an application.
Finally it is just really really fast, even if it does enjoy eating RAM.
The extensions are also really simple to add and manage for chrome and the fully customisable theme (I even made my own themes at one point XP) makes it quite adaptable.