I have owned both. I owned the Prism for a short while. Paddled it once and really did not like it and sold it shortly afterwards.
The Advantage to me is noticeably faster, narrower and tracks better. It is fast yet still relatively maneuverable, but a good bit less stable than the Prism.
To me the Prism was like a dog, and was super wide which hindered a good vertical stroke.
The Prism may be better for you if you want it for wildlife viewing and tootling around, carrying gear, etc., but if you want a fast and fun boat the Advantage is much better in my opinion.