My vote goes to Alabama. Its younger voters are more supportive of Democrats than those in Oklahoma (e.g. Exit polls from 2008 indicated that Obama won voters under 30 in Alabama but lost among this group in Oklahoma).
Oklahoma whites are more Democratic than Alabama whites. Where did Obama do better with white voters under 30?
From 2012 (according to the NYT):
Alabama Whites under 30: 20% Obama
Oklahoma Whites under 30: 30% Obama
So, he didn't do that well with young whites from either state, but Alabama is significantly more black than Oklahoma, so his overall percentages with under 30s in both states were:
Alabama: 48%
Oklahoma: 42%