It is difficult to say, as neither animal may be kept as a pet. Also, platypuses and hedgehogs are found in completely different parts of the world. No doubt platypuses are more popular in Australia. However, as hedgehogs are found in Europe, Asia and Africa, where there is a larger population of people to have an opinion either way, hedgehogs are likely to be more popular.
Bob the Builder is more popular than Sonic the Hedgehog. There are many more toys sold.
Most likely, Sonic the Hedgehog is more popular than Gordon Brown because I have never even HEARD of him.
More than one platypus is two or more platypuses. The plural is not 'platypi'.
I guess it would depend on the generation. My hopes are that the correct answer would be sonic the hedgehog because sonic knows no social, economic, or other boundaries within where his existence is present.
Sonic the Hedgehog is more famous than The Simpsons
Lady Gaga is currently more famous than Sonic the Hedgehog.
The way political correctnes goes these days, platypus probably have more rights than you do
Sonic the Hedgehog is better known to both generations so Sonic the Hedgehog is more famous than Cookie Monster
There has never been more than one species of platypus (except for a prehistoric platypus as shown by fossil remains). Platypuses in the north, like the koala, are smaller than their southern counterparts, but they are still a single species.
An echidna is the only other egg-laying mammal than the platypus. It lives in Australia. They are also called spiny ant-eaters, and their appearance is similar to a hedgehog.
While fans of Sonic the Hedgehog believe he is more popular, the question is about fame. Sonic the hedgehog is a fictional character from a video game, whereas Barack Obama is the president of the United States. Not everyone plays or has access to video games, and besides, video game characters are not necessarily popular for more than a few years; but all over the world, people do know about America and who our president is; therefore, it would be safe to say that more people world-wide have heard of Barack Obama than about Sonic the Hedgehog, making President Obama more famous.
unfortunately, you misspelled platypus. it is a common mistake though. more than one platypus are platypi.