Micarta, any day of the week and quite a few times on Sundays - if you ask me. Micarta is softer and grippier, G-10 is harder and 'sharper'. Micarta also seems to absorb impact shock a slight bit better, but that may be just me. Also, Micarta is cheaper, which doesn't exactly hurt for a user. Micarta is lighter, too, leaving the blade that much more blade heavy but lighter overall.
There is one caveat to Micarta, though: it does absorb fluids, which may be a problem if you intend to really get messy. It's not that bad, though, just takes some cleaning and time.