It all really just depends on the situation. I can think up situations where I want the walk, and other situations where I give up the out to get the sure (or high percentage) run, and other situations where I'm willing to risk the strikeout to give a hitter with a good slugging percentage and/or high career BABIP an opportunity to swing away for a big inning. This is why it is ideal to have a lineup filled with players who can do many things well with the bat. Short of that, at least give me a broad set of hitting skills throughout the lineup. And that's why a manager needs to have both the most up-to-date metrics and splits, and a good intuition, to make more calls that result in runs being scored.
Back on point, with the way the Sox roster presently is constructed, Rios is the best fit to hit third.
The universe is the practical joke of the General at the expense of the Particular, quoth Frater Perdurabo, and laughed. The disciples nearest him wept, seeing the Universal Sorrow. Others laughed, seeing the Universal Joke. Others wept. Others laughed. Others wept because they couldn't see the Joke, and others laughed lest they should be thought not to see the Joke. But though FRATER laughed openly, he wept secretly; and really he neither laughed nor wept. Nor did he mean what he said.