Where I work, we use both species and I would recommend cane toads because of their adaptations for an independence from water. Cane toads simply are more likely to deal favorably with the stresses of transportation, handling, and exhibiting. I also think that people or far more interested in a toad that is 25 times the size of any toads they have ever seen. Most everybody has seen a bullfrog. Both of them have a huge conservation component to their natural history, where they have been introduced into foreign habitats and are responsible for the decimation of numerous species abroad multiple taxa. For that reason, I would not recommend buying a bullfrog and then letting it go in any pond other than where it came from. It does not matter if the species is native to your area, the localized genes that will come from the bullfrog you buy will not be native. The cane toads can be purchased from Glades herps in Florida (gherps.com), where they are also introduced. In fact, you're probably due in the people of Florida a favor by buying them!
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...the oldest task in human history: to live on a piece of land without spoiling it."
Aldo Leopold (1938)
"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us."
Calvin and Hobbes (Scientific Progress Goes 'Boink', 1991)