If this was day 1 and I still had the knowledge I do now, I would tell you to focus on both. I'm already done with red and gaining anymore is just a waste so I'm stuck doing nothing but blue. Ragnarok gives 3 souls at random and me getting anymore Devil Soul is a no gain at all since there is no benefit to getting more than 150.

But since this isn't day 1 and you have less than 2 days left, assuming you're just starting, unless you're using a water team, I would recommend you focus on the eidolon.