Its just that open source communities have the most vocal proponents, but the closed source users tend to keep quiet and just get to work. Generalizing to some degree of course
And SBCL comes from CMUCL, most of the best parts of it are from that stellar implementation
LW has better package delivery and a stellar GUI tool. LW is otherwise slow and requires non-portable APIs to get reasonable performance for some kinds of low level code.
SBCL is cheaper, way way faster (in almost every dimension), more portable, better integrated with most OS environments, and provides better static diagnostics. It suffers from having a meh garbage collector and meh delivery mechanisms.
CMUCL is still 32bit, AFAIK.