You don't mention when to use one profiler over another. My rule of thumb is to try Devel::Dprof first. If that core-dumps a few times in a row (it can do that, depending on your code) then I try Devel::Profiler.

Another module worth pointing out is Devel::FastProf. The two main profilers profile by sub/method call. If you've inherited a nasty monolithic script FastProf will give you profiling by file line.