Fink or Macports?
metachor: Both and neither.  On a case-by-case basis, I will do some light google research on the experience of the mac-unix community for that particular package.  Sometimes either the fink or ports release is recommended over the other, sometimes a stand-alone installer has been made, and often I just choose to compile from source.  The decision is usually based on factors including latest version available (fink and ports are not always up to date), reported stability, dependencies (I might already have some of the dependencies obtained by one particular method), etc.  If the choice was just between fink and ports on their merits alone, I slightly prefer ports, but that is probably a religious decision (a la vi vs emacs, etc...).