Macports has always seemed to me to be a more "unix-y" way of doing that, and it works politely with Apple's ways on top of the Unix core (eg locking down the system volume).
It also has a very nice "select" and "variants" system that allows you to have multiple versions of a package as well as packages with more or less functionality (eg integrating with the MacOS keychain etc).
When I first got into Macs (only around 5 years ago), I looked at both homebrew and macports and as soon as I saw homebrew blasting stuff into /usr/local while macports neatly put everything in /opt, I was convinced to go with macports. I also had previous experience with the BSD's port systems, which helped push me towards macports.
But I'm open to being convinced about homebrew, although I've never needed something that it had that macports didnt.