We're actually using Mantis for our projects. Or should I say "we try to use". The problem with all bug trackers I know is that they're made by programmers, for programmers. So the design is non existent or totally absurd.
Of course, as a programmer, I can use mantis without problem, but how useful is a bug tracker when all the people involved** in a project find them so badly designed and so hard to use that they prefer making Google document with bullet list of the bugs they found or suggestion they might have.
I'm about to install a forum, it seem to me like a "in the middle" solution between a bug tracker and plain bullet list. At least a forum allow to monitor, and to centralize a discussion about a suggestion.
In case my concern is not clear, my question can be summarized to:
How do you handle you bug&suggestion report toward the non-technical user ?
** By involved, I DON'T mean the actual client or the end-user. I'm thinking about our integrator, project managers, and those who are involved with the QA.