You're confusing dialects and implementations.
CL is a popular dialect. SBCL is a popular implementation of it. There are others.
Similarly, R6RS & R7RS Scheme are two more popular dialects. Chez is a popular implementation of R6RS, again there are others. Not sure which of the implementations of R7RS are more popular, maybe Gerbil?
Personally, I like the ISLisp dialect too, but (unfortunately IMHO) it's definitely not popular. Whether popularity matters at all is a matter of opinion.
I wouldn't class any languages very different to the above as Lisps, despite people's attempts to shoehorn Python/Ruby/JavaScript into that definition.