High utilization on two of my credit cards dropped my credit score by 40 points! Paying them down to 45% raised my credit back up 40%, having under 30% raised my credit 30 more points, they are equally important.
I'm not a pro, I'm just speaking from direct experience, what better than to get a suggestion from someone who has actually experienced it. To many systems have different ways of calculating debt, having over 50% utilization on your CCs is the first fix, the second is lowering your debt over all. Of course if you’re looking at fixing your credit over a long period of time and not worried about raising your credit score quickly than you would choose to pay down the cards with the highest APRs first and than lower the debt ratio on cards with low APRs. The answer to your question depends on if your working in general to reduce debt or attempting to raise your credit for a loan offer or buying a house etc.
Also as a heads up if you go to apply for a loan somewhere ask who their lenders are, call the lenders first and ask how they calculate for lending. I wish we would have done this before we applied for an RV loan and were denied. We could have corrected a few things first before applying. Now all other lenders just see a denial and run for the hills. Of course no one would tell us this because why do they really care about our credit score, they just want ya in and out, you either qualify or get out of their hair! (Denied on a $14,000 dollar RV loan with ½ down and credit score of 730 because I was previously denied by a lender because of a discrepancy on one of my reports). I fixed it and three months later with fairly good credit I was still denied because the two lenders saw the denials and ran for the hills.