Trac was perfection. Self-hosted and just the right amount of features.
I remember being interested in MantisBT and a few others (Launchpad for BZR?) mainly because it seemed they made a bunch of decisions for me.
In retrospect, it was probably the flexibility of projects like Bugzilla that heralded the "opinionated" approaches to software that followed. In many ways software also follows the patterns of the language they are written in . Bugzilla was written in Perl, so of course there is more than one way to do anything.
I had forgotten about Mantis, but that was the first tracker that the non-programmers in our group were comfortable using. It is a bit funny how quickly we all migrated to Github as a larger community as it became the default for just about everything.