What kind of question is this? Each of the tunings has its own strengths, such as the third on top vs. the 5th on top, and so forth, but what are you going to use it for? If I were considering which is best for instrumentals, and not trying to accompany vocals, then I might see which one gives me (the player) the most flexibility. I have a harder time with C than G, partly (probably) due to familiarity because of the banjo (open C is a string-buster for banjoists, so I don't use it much). So for me, I would choose open G, because it'd be easier.

However, it might be more unusual to use C, and therefore more interesting to an audience. And if specific effects were not an issue, it might be best to choose the less-common tuning, since you can hear open G "everywhere."

So basically, I'm asking why you're asking us. If you know what you want, go for it. Try both, see which one fits YOU. Then YOU tell US which one is the best.

Ed