I haven't seen Harrison pitch in person, but based on his stats this year, he seems to have figured something out since the beginning of the season. You won't get much K's from him since he's never been known as a strike out pitcher. His WHIP is a bit above average, although he does tend to walk a lot of guys now and then. Solid, middle of the rotation kind of pitcher. In fantasy terms, a decent 3rd or 4th pitcher.
Lohse, eh. He tends to fade in the 2nd half of the season, so I wouldn't go out of my way to pick him up. His numbers this year are skewed quite a bit because he had a pretty good first half. He's also not a high K pitcher, but his WHIP is generally worse than Harrison's. If I had to choose, I would take Harrison before Lohse.