ZenCart. The licence does not exclude adult sites, HIGHLY configurable, intuitive once you learn the scheme (and it's very similar to other carts), PHP based, FREE TO ANYONE, LOTS of extensions and extras to help it out, templates galore and ready to use.
I use it with
http://blackrosefloggers.com and it's FANTASTIC. I love it and wouldn't change it.
Did I mention it's FREE?