I have both. I love Skogg for the simplicity as well. You get a lot done in a short amount of time. It has by far the best tutorial of any I've seen and I really like Michael's demeanor.
I like parts of RKS for the variety. I thought workout one with the swings only would be boring but I actually like it a lot. But I can tell you that I'm never going to do 30 minutes of snatches. Just not interested!
I don't think I'm a good one to answer about the cardio vs strength training aspect because I think all kb work has a cardio effect for me. As for strength, I think it all depends on how heavy you go with the kb. And again, all kb workouts have strength training effect for me too.
Not much help was I??!!