Our venue offers cake packages from either of these vendors so we recently checked them both out at tastings. Here is my review:
Kondeiter Meister- was high volume with appointments; quite crowded and not as personalized. The great thing was they gave us samples (and HUGE peices that we took to go as well) of their 18 flavors too. Their cream is unique; very buttery/creamy. Cake not as moist as Icing on the Cake but we were sold on the pumpkin maple that we will use at our fall wedding. They are more expensive for anything outside of the package (ie. $75 for some fondant leaves on cake) and I didn't feel like they would necessarily copy my vision of what I want exactly but still our top choice.
Icing on the Cake- VERY personalized. You meet with the owner who is very nice. Samples weren't as generous- ie. we were only able to choose 4-5 samples of the dozens of flavors and slices were small. However, for extras they were cheaper and offered more options, more personalized. They also offer a free anniversary cake if you take a picture of your cake the day of wedding and send it to them! We felt more at ease there, confident that she could meet our needs moreso than KM but they don't offer fall flavors
Cake was more moist and frosting good too. Can't go wrong with either places but KM got our final vote!