Melbourne may contain more "Freestyle" moves. However, there is little reason to think that one is better than the other. Both of these dances are based on personal preference.
But, to name a few points in leaning towards Jumpstyle.
1) The Melbourne Shuffle has evolved so much in the essence of the dance itself, and the music that tags along with it. LMFAO has helped spark the Shuffle "Revolution", as terrible as it may be. Something that used to be special, underground, and fun to do (since not many people knew how to do it), has become something commercialized, "popular", imitated, and altogether corrupted.
2) As a result of LMFAO, the stlye of clothing worn for Melbourne has been Phat pants, with reflective tape, and hoodies. Now, it has become skinny jeans and t-shirts ith loose chains, on occasion. There are still people who wear the "Traditional" outfit style... But altogether, the "Norm" has become what LMFAO has corrupted it to be...
3) With Jumpstyle, the styles are always changing, to an extent. It may not require as much effort, but it is still a very good workout for you Quads and Hamstrings, whereas the Melbourne is good for Calfs and Ankles.
4) There are "tricks" specific to Jumpstyle that Melbourne does not offer, such as Duo-Jumping ((which I guess you could say there is "Duo-Shuffling" /Side by Side)). The music with Jumpstyle has mostly stayed the same, as well. Only Hardstlye/Jumpstyle-based music is able to be used with Jumping.