I’ve been using Ultrakeyer, Primatte and Advantedge over the years, in combination with every single other matte creation trick available to me in Fusion. I wouldn’t recommend either as a complete solution, though. They are all very different beasts, with their strengths and weaknesses. That said, Advantedge and Primatte combined are very hard to beat. The spill suppression in Utrakeyer isn’t too shabby either. But all depends on your source footage. If you are lucky enough to deal with crispy clean blue/greenscreen all the time, Advantedge is pretty awesome. Although I have encountered quite a few stability issues with it on an otherwise very stable setup.
I believe, in the lastest Fusion, Keylight is now supported as well, through OpenFX (if I am not mistaken).
Hope this helps.