Today i updated my FreeBSD port of the ATOP full-screen performance monitor to the recent version. PR is already sent, it should be in a port tree soon. Atop is one of my favorite tool to monitor performance not only because it shows much more then system TOP(1), but also because it allows to record all activity to binary log to work with it later or generate different reports.
FreeBSD port supports all Linux version functionality except per-process network utilization (netatop). Netatop module porting/replacement is not something trivial and will require kernel patching.