Supplying devices to a testing team of possibly close to one thousand testers and developers is a great undertaking but Sauce Labs has made this very easy and a welcomed solution.
As stated earlier we use Sauce Labs for a combination of automated testing and manual testing. Therefore the most useful features are the ability to run the functional automated tests via a Sauce Labs tunnels which allows access to applications in our internal network. The second most useful feature is the manual side.
The most valuable feature is the cross-browser feature, it has many android and iOS devices both simulators and real devices. It's easy to integrate. I also like video recording too.
Sauce Lab analytics helped us to get detailed knowledge on test cases execution and logs.
I have found the live test section with Sauce Labs to be extremely valuable. When you can't quite figure out why a test is failing, you can go to the live test results section within their tool and launch your test (specifying a given OS/browser, or device) manually and step through the test to see the issue more clearly, usually opening up the developer's tool console and watching the network calls and console (within Chrome) to usually find the underlying issue.
The insights section provides a great overall state of the automation suite and can identify trends relatively quickly. If we see a dip in our passing rate over time, we can look at what changed when the test started failing to find the root cause rather than doing a quick fix to find that the test fails a short time later.
Live device testing. As we all know, It's really hard and challenging to find/purchase many real devices to test because it will be costly and not all the team can be able to purchase all of the devices out there. We used to have a lot of real devices under our labs. However, it is really time-consuming to maintain those devices and make sure they are up to date with the testing requirements.