The worse coach has to be Childress, mainly due to what others have mentioned: he's doing less with more.
Lovie Smith has great players, no doubt about it. But for every good player Lovie has, Childress usually has one better.
Favre and Cutler are both INT prone QB's, even though Favre had a miraculous season last year. Some people say Favre, others Cutler, I say it's basically the same thing.
Adrian Peterson alone is better than Matt Forte and Chester Taylor, probably even combined.
Randy Moss, Percy Harvin, Visanthe Shiancoe, Bernard Berrian, Greg Camarillo, Greg Lewis, and Sidney Rice make up what could very well be the best receiving corps in the NFL. The Bears have Hester and Olsen and Knox, and that's about it.
Lovie has Peppers and Childress has Allen. But Childress also has the Williams Wall and Ray Edwards, who's a more than solid DE. This is one of the best defensive lines in football.
Lovie probably does have a better LB group. Urlacher and Briggs are good players, while Henderson and Greenway are good too, but not at the same level.
When it comes to defensive backs, again, I say push. Winfield, Griffin, Johnson, Williams, Abdullah is an average to above average unit. But the same thing could be said about the Bears. Young players, but not an elite unit by any means.
Minnesota should have fired Childress long ago. There are many teams that fare just as good as the Vikings with much less talent.
If the coaches were in opposite teams (Lovie in Minnesota and Childress in Chicago), the Bears would have never made the Superbowl and the Vikings probably would have won some more games.
Anyway, that's just my opinion.
Props to clover_jeez!