That depends on what you want to do.
While there's a little overlap, the two programs both excel at different things.
ArtCAM is targeted more towards woodworkers and signmakers, while Fusion is more of a mechanical type program.
My personal opinion, is that you can get g-code out of ArtCAM quicker and easier, as it doesn't have the million different settings that Fusion has.
There is no one CAD program that does everything well.
I use 4-5 different CAD/CAM programs, from Fusion 360, to Aspire. But 90% of what I do are done with simple 2D drawings and basic CAM, like Cut 2D.