its been a decade, so I figure I'll chime in:
Sonar Automation PROS:
-Simple to setup
-easy to edit, draw and manipulate the envelope
Sonar Automation CONS:
-no CC data is recorded, so cannot export MIDI track to another DAW or save it for archival purposes
-can't control per-note parameters as good. In PRV it is easy to simply click under a note and set a controller value for that note. In Automation, you can draw curves, but not per-note values.
MIDI CC PROS:
-ability to export MIDI track to another DAW or save it for archival purposes. Just keep a notepad file of the mappings between CC -> parameter, then you can use the VST in another DAW or even Sonar but in a new project
-can edit per-note parameters (see above)
MIDI CC CONS:
-manual setup of CC to synth mappings everything you use the synth.
-drawing curves is not as easy as automation lanes (however recent PRV changes have improved this)
Am i missing anything here?