Detroit for me but it's closer than people think.
Seattle has a better rotation, particularly if Woo can pitch. That being said, Detroit has the best single SP and Seattle's starting pitching is overrated because of their park. The fact that Skubal would be the Game 3 starter and you could potentially close out a series having only faced him once is pretty big here.
Seattle has a better bullpen, or at least some better late inning options. Detroit's is pretty boring.
Seattle has a better offense. Top 5 in wRC+ since June 1st.
Seattle has a bad defense. Detroit's is not good but it is more average.
It's the offense alone that I would want to avoid. The top 6 in Seattle's lineup is just very good, and they could hit anybody, and they have a couple of true stars who could get hot and dominate all series.
Detroit does not have that star on offense. You can pitch to Torkelson, Greene, and Kerry Carpenter. Detroit does have more bench utility so they will pinch hit and change their lineup more.