Well, fusion has no byproducts to dispose of,

Fusion has a silly-high neutron flux, unfortunately. Aneutronic fusion... good luck with that.

Fission - decent fission cycles, not the silly strawman that people like to bring up ("once-through" and the like) - actually has less byproducts than fusion. It's the 'chop one twig off of a tree and burn it then call the rest waste'-style approaches that are terrible.