Without knowing a whole lot about Wake Forest, it seems this info is generally good (maybe biased a little against Michigan, but that is hard to say from my perspective as Michigan is the program I am more familiar with).
As far as the XC programs are concerned, Michigan has done quite well under Sullivan. Big 10 titles and top 10 finishes at NCAAs are pretty common for UM recently - it remains to be seen whether they can make the jump to be a program on the podium at NCAAs. If I were a runner looking to make a difference between top 10 and top 4 at NCAAs, Michigan would be a good place.
I'm not sure why the success on the track hasn't been as consistent as in cross country. Clearly, Sullivan was able to bring home titles with Ferlic and Flanagan, but the overall depth in track has been a little less than I'd expect. Maybe UM has more success in XC than track because summers are great for training in Michigan, and winters can be tough? Maybe Sullivan was such a talent as an athlete that his own training experience doesn't translate quite as well to his runners? I know a lot more runners who ran for previous coaches at UM than under Sullivan, but based on everything I've seen, Michigan has a solid foundation for success on the track currently.