Best color profile with new macbook?

What is the most accurate color profile with the new macbook? How do I know if what the audience see is the same I see with the color profile on my macbook?

Display profile is information describing your display colour output behaviour. There are two possibilities:

• you look at the specifications of your display to learn what colour profile it was factory-calibrated against and select it as display profile (refer to your OS manuals to learn how it is done or this SU question)
• you profile your screen with a colorimeter or spectrometer and select the profile as your display profile

There are no other ways of making yourself sure you are seeing actual colour as defined by ICC. Other than that you can never be sure that the audience will see exactly what you do because not all software respects ICC standards and not all displays are profiled/calibrated.

The question now is this: considering I have friends with both windows and osx, what is it likely they see?

Thanks to standardisation work It does not depend on the OS but it does depend on the particular software used and whether the display conforms to sRGB or is profiled if it does not.

Typically a web browser is not set up correctly for correctly viewing colorimetric images by default, neither Chrome nor Firefox are (I have not researched other browsers). They will display images correctly in 100% of cases given that:

• viewer has an sRGB-calibrated display
• image has an sRGB colour space

Many modern displays conform to sRGB well but from those which don't only a small fraction is profiled.

I found that Color LCD and Apple RGB are the best, at least for me. In particular, Adobe RGB is more saturated while Color LCD is more washed out.

Judging by what you say (you are seeing more saturated colours with AppleRGB) you are artificially mismanaging your image information using Photoshop/Aperture/whatever.

Image colour space is information describing the storage of colorimetric image information. Practically colour space sets the colour gamut which can be used in an image.

The setting which you are altering is image colour space and it does not affect whether what you see on your display matches what viewer sees (except when viewer's display has smaller output gamut). Essentially you should never assign colour space to an image unless there is a very specific task requiring so.