Why I use MacPorts instead of Homebrew

Henno sums up my opinion nicely:

The fact that Homebrew tries to use libraries from the base OS X install is nice if you are concerned about disk space, but can be a disaster if Apple ships some old, custom or incomplete version of these well-known libraries. At least MacPorts has control over these dependencies, which increases the chance that everything actually compiles and links correctly every time, all the time. Other than the Xcode toolchain itself, a cause of a failure is now in a location they control: their ports tree. Yes, they could patch their way around things that Apple has decided to do differently, but IMO it is tidier to just install everything with as little vendor-specific customizations as possible.

And when you want to install something that needs a dependency version that is around for ages, but which Apple never bothered to update in their OS, then you lose this Homebrew advantage completely anyways because you have to get it installed yourself. Which is also handy when you want complete control over application behavior regardless of OS X version. It becomes more predictable.

Disk space is cheap. A solid, stable system is so much more important than a convenient one.