I've seen most of what is on the list, either in magazines or on the web, occasionally in an LFS, but always the most impressive is the Arrowana. A tankbuster maybe, but one that most people would aspire to keep if they had the means.
Since the Archer Fish wasn't a choice, I had to go with the Butter Fly fish. Although I didn't realize that the Arapaima / Pirarucu is considered to be an arowana. Had I known that I would have voted for the Arowana.