The ones marked "debug" or "-d" are debug builds, to be used only if there is a problem (such as your error issues... they give more detailed info on problems encountered). The ones without the debug or marked with "-r" are the normal builds to be used when everything is working right.
Now, 3.6.9 is the last released stable branch. The "trunk" build is a more recent, experimental, but still mostly stable build. It's more advanced, but not completely debugged, so if you encounter errors with it, tell the SCP people (preferably using
Mantis) so they can fix it for the next release.