Nginx has been added to the OpenBSD base system which means it has been security audited and will someday replace the fork of Apache 1.3 as the primary httpd in OpenBSD.
We already moved to Nginx on OpenBSD before 5.2. It was a nice surprise for us when this happened and, although it's not the bleeding edge Nginx release that's available, it was much appreciated since that meant upgrades wouldn't be as difficult from then on.
I should mention that Apache had been good to us in the past, despite being the 1.3 series with patches bundled with OpenBSD, but we were expecting far more from it than it was originally intended to do. In that regard, configuration and deployment became much simpler since we moved to Nginx.
Went to nginx on OpenBSD myself, mostly because at some point the latest lighttpd was not playing well with the latest OpenSSL. Never looked back since.
You may have seen the same or related problem, since it takes a bit while for packages to come to OpenBSD. But either way, you ended up with something that worked well :)
http://marc.info/?l=openbsd-misc&m=134684032310189&w=2