Personally, I prefer the output of Voxelizer to Slic3r, Cura is decent enough, and even built into the print server I am trying out (OctoPrint).
Raise3d's Ideamaker slicer has been making the rounds as well. I know people sing its praises, but there are a lot more slicers out there. There are illegitimate means of obtaining it, but the few that I have found, my antivirus screams to high heaven about, Trojan downloaders embedded in the executables, a few versions behind, etc.
