KiCAD is completely unlimited in the number of layers and size of board space you can use.
1 That, to me, sets it far ahead of all other free EDA software.
To be totally clear, excepting the FPGA development tools, fancy autorouting algos and other gimmicks that maybe 1% of users ever touch, Altium is no better than KiCAD. Anyone who says otherwise has not fully learned KiCAD and/or refuses to adapt their workflow, due to laziness.
2 That, or they're in the 1% that is required by their employer to use Altium.
I find KiCAd comparable to
LaTeX. Yes, KiCAD and LaTeX have somewhat unfamiliar interfaces for noobs and those used to "professional" tools like Altium and M$ Word, but in the end they usually make a more beautiful result, are less buggy, and are more efficiently written.
1 Within reason. Obviously you can't make a board that's 64 layers deep, since that isn't manufacturable with current technology.
2 I will be the first to admit that I refuse to change my workflow, at least at this time, from KiCAD to Altium or god forbid Eagle. I have used Altium (the full version with all the bells and whistles) and its most basic functions are buggy as all hell. The interface is hideous and the bloat of 7GB (and the price) is unacceptable given that they didn't include modules/parts for every single component in existence.