Arnold!

So I've been playing with SolidAngle's Arnold renderer and I'm having a blast. It's so simple to use and will get you really nice results pretty quickly. It uses a different method of sampling that lets you keep your renders low quality for quick look development, and then when you're ready to render, you turn up your samples and get a high quality render without worrying about the look changing (ie no need to worry about using low-poly stand-ins or final gather settings, etc). Both Digital Tutors and FxPhd have in depth tutorials on using and optimizing Arnold, but there are some good free tutorials floating around as well. One good one I found was by Sony's Jon Tojek, which manages to cover most of the basics in about 20 minutes. Even though Jon does cover linear workflow in his tutorial, I found another video that is a quick and simple explanation of setting up linear workflow in Arnold, for anyone who doesn't want to scrub through Jon's video to try and find the right section.

Jon Tojek Arnold Tutorial

Linear Workflow In Arnold