All sponsors of Elemental Selenium are companies that I actively use in my testing practice and would happily recommend even if they didn't pay me to help keep the lights on.
I encourage you to check them out!
Sauce Labs is the leading Selenium infrastructure provider. If you're looking to run your tests on a myriad of different browser, operating system, and device combinations. Then look no further.
They have over 800 different combinations to choose from. They make it easy to get started and even easier to scale your test execution. Going with them is a no-brainer.