First of all, I'm not new to this. I'm the admin for eschergirls.com, which was originally a Tumblr only blog until they were bought out. Websites and infrastructure are also my day-job. So this isn't untested advice.
Wordpress.com's TOS likely also does not mention NSFW content. An [old support forum thread)(https://wordpress.org/support/topic/adult/) suggests that it is allowed. This service also is the most portable, as you can export your content and self-host in the future if that changes. Wordpress.com also tends to be more reasonable when it comes to legal threats from the MPAA and RIAA and other copyright mongers.
@socketwench I have a wordpress site. Mature content such as nudity is allowed, but porn is not. In the case of mature content, the way to get the site marked as mature is to report your own site, which gave me a lot of anxiety but came out fine.