Best Mobile Testing Tool

Can anyone recommend the best tool or tools for testing mobile apps and sites? I need to test them on Android and iOS devices, both web apps and mobile sites. I have seen numerous emulators and looked at the SDKs, but the emulators do not seem that accurate and I would prefer to find one tool to do everything if possible rather than installing multiple SDKs. Are any of the cloud based testing environments worth the money?

Thanks in advance for any advice you can provide.

The only one I know of that does a good job of testing different devices using different browsers.

It also does live rendering for a specific device which will allow you make your edits using your editor tool and then refresh the specified device to see the results.