The first thing that comes to mind is the ability to automate the build process in a seamless way and run workflows effortlessly. It supports parallel builds so it can scale well. Also, it covers the basics of any build and integration tool, including email notifications (especially when tests are fixed), project insights, etc. 

For us, this translates to high degree of productivity, ability to detect exactly which build failed and why, and being able to push multiple builds to our production environment at a very fast rate. This has increased the velocity of our product significantly.

save our money for buying plans of browserstack or sauce labs

save our time, do not need to setup our own xvfb, selenium grid or other stuff.