You may want to watch the Emmy award winning Zacuto Shootout video series. They assembled a small team of cinematographers and DSLR experts. They performed a variety of fairly scientific camera tests on a number of DSLR cameras, and also put them in direct comparison with 35mm film. Participants included Robert Primes, ASC, and Philip Bloom, among others. They took the resulting footage to a first rate color grading suite, and projected the results in several first rate theaters, including the one at Skywalker Ranch, and showed the results side by side to an audience of cinematographers and industry professionals.
Here are the settings that I have ended up using on my Canon T2i. They are based in part on the Zacuto Shootout results, and also on my own tests and preferences:
Highlight Tone Priority: Off
Auto Lighting Optimizer: Off
Movie Exposure: Manual
Picture Style: Faithful
Sharpness: 0
Contrast: -4
Saturation: -2
Color Tone: 0
The big difference between my settings and the Zacuto Shootout settings is that I decided to use the Faithful picture style, while they used the Neutral picture style. I decided to make this change because in every test I have done, I liked the look of skin tones better with the Faithful picture style.
According to Canon's picture style documentation on their web site, the Neutral picture style provides the most latitude, while the Faithful picture style provides the most accurate color.
Personally I found that the latitude was fairly similar between them with the contrast all the way down at -4 and the saturation halfway down at -2, and that I cared more about the color accuracy than the small differences in latitude at that point.
If you have a Canon DSLR and a computer in front of you, you have a couple of options for doing your own A/B tests. You can shoot video of the same thing using multiple picture styles and compare them. You can also shoot RAW images and use the Digital Photo Professional software to apply picture styles to the RAW files. In this way, you can compare the results of multiple picture styles after the fact on the exact same images. I went through several dozen random RAW pictures that I took in a variety of geographical states and lighting situations, and personally I preferred Faithful over Neutral almost every single time.
I have learned from reading David Mullen's posts that he has a philosophy of getting the image halfway there in camera, and then getting it the rest of the way there during color grading. To me, the Faithful picture style seems more in keeping with that philosophy, at least based on my personal experience.
Your mileage may vary, and I would encourage you to perform your own tests to decide for yourself which picture style(s) you like better. Shoot some footage in different lighting conditions and locations, and try to grade it. See which one gives you the best results for your projects.
I haven't played with the third party picture styles too much, but based on some of the tests I've seen, it seems that some of them can do horrible things to skin tones to get a little bit of extra highlight and shadow detail. You only have eight bits per channel, and if you're stretching them too far across the light spectrum, you will necessarily capture less detail on the critical midtones. Again, I would do your own tests before going with what someone else recommended, including me.
Best of luck, and happy shooting!