excuse the bluntness there, i was on my ipod.
to expand - oats rule because of their slow release energy and relatively high protein content. weetabix is 10% protein, oats tend to be about 11%. negligible difference on paper, but not all protein is the same - weetabix is (rather astonishingly) very high in wheat so its protein content is mostly gluten - do a quick search on that and you'll see it's the last thing you want to have in your diet...it's the active ingredient in alcohol that leads to the dreaded 'beer belly' among other nasties.
by comparison, the protein content of oats is varied but it contains more leucine than almost any other non-meat based food - leucine is the protein believed to be most important in muscle growth and maintenance.
no contest really, avoid high-wheat foods in general.