In total I got 33 responses from zoo nerds who were willing to fill in the questionnaire, a big thanks to all of you!
When analyzing the results I found relatively high agreement across most users on the popularity of most groups/species groups (more about that below). When comparing to the little available literature my results are pretty comparable overall, with the same species mentioned as popular. The big exception to this are otters. Small-clawed Otters only come on rank 41, below flamingos, lemurs, manatees and others. But this is an exception rather than the rule. In general my results also show that mammals, especially large ones, and active animals are more popular, just as species which have a high cuddlyness factor. in total there were 21 species that were given on average 35 points or more out of 50, shown in the graph below:
Note that you cannot say based on just these data that e.g. penguins are more popular than sea lions, just that both are among the most popular taxa. It is also important to note that a priori popularity (attractiveness) doesn't necessarily mean that visitors spend time looking at these animals in practice. That also depends on interactions, animal activity and likely on enclosure design. As an example, nobody would give high points for Fiddler Crabs on attractivity, but people in Burgers' Zoo spend a lot of time observing these animals, due to the enclosure design.
The least popular species (groups) were amphibians, small birds, Elephant-shrews, small rodents, waterfowl and fowl and hedgehogs. Echidna and Hyrax also didn't exactly score many points, just like other small mammals and ectotherms.
There was relatively high disagreement (based on standard deviations) for several groups. Most disagreement was about how popular (in decreasing order) Whale Sharks, Belugas, Manta Rays, Platypus, Octopus, Peacocks, Orcas, Clownfish, Dolphins, Ostriches, Komodo Dragons and some other fish groups are for the general zoo going public. So generalizing, there is higher disagreement for popularity of fish, birds and animals about which there are serious welfare concerns.
Stay tuned for more, such as which European zoos have the most popular collection, both in total score, but also relative to their total species richness.