Seconded (no karma available).
We're on our third Nexus 5 (all off Swappa used, they are $200 now...) after my wife took her's out of the case and cracked the screen real good (it's the backup phone now, just did the transfer yesterday).
Mine has a good case and has survived falls where I expected destruction (5 foot drop onto concrete, with direct corner impact). Get a good case.
Very solid with Kitkat and Lolipop. Still very powerful regarding performance.
For the record I did like my iPhone 4 (it was rock solid, but never updated and new games required the updates), but wanted a more open development environment for my phone platform.