My husband and I did an adults only
AbD (London/Paris) and my best friend and her husband did a Perillo. We have done a comparison and I do believe that AbD is quite a bit better.
The biggest difference is that Perillo has an agreement with certain vendors. These vendors provide advertising funds to Perillo for their brochurs, etc in exchange for Perillo tours stopping at their places for mandatory "shopping" time. In Florence, they go to a leather goods store and have to go through a spiel on how leather is made. They go to a wood making place in another town (I don't remember where she said it was) and they went to a glass place in Venice. I don't recall if she said they did anything in Rome. These are not short stops either, she said at least an hour at each of these locations. And there is a feeling of expectation that you will buy something. Someone on their tour complained to the guide about these stops and the guide told them to take it up with Perillo's headquarters because Perillo had this agreement with these vendors and the guide had no lee-way in skipping these venues.
Other than that, it seems like the tours were pretty equal. They have also done an AbD and felt that the guides were equal, the accommodations were equal but they really hated those stops at these stores (which may explain why they can offer cheaper tour prices).
Perillo did offer a tour that did not include meals (this is the one she went on) and that would be amazing as I felt the food on our AbD was uninspiring and the only thing I disliked about doing a group tour. I have traveled Italy on my own and I would hate to have missed out on the great food I had.
I don't know anything about Globus.
