This question is almost meaningless - there are so many variables here that you could write a book on them. Urban or rural? Height above ground? Frequencies you really want to hear? Scanner or professional radio (i.e. R7000, AOR5000)? Area(s) of interest? Just too many possibilities here....73 Mike
Uniden Bearcat BCD996XT Scanner, extremely rural, 1700 ft. up the side of a mountain in the Cascades, would like to hear all the most popular "rookie" bands CLEARLY. Circumstances dictate I choose one or the other. Sorry the question was so ambiguous, but as you've obviously discerned, I have absolutely no idea what i'm doing...
Although the discone has no gain, it will do better across a broader range. The Ferret is tuned to 8 bands (from memory as we don't have that brand in Australia). This means you will get better or equal reception on the bands for which it is tuned, but average or worse reception across those parts of the spectrum for which it is not tuned.
In the end it comes down to how much you want to spend, what you want to listen to and whether or not you will end up wanting to explore wider parts of the radio spectrum. For mine I would say go for a good discone and get it up as high as you can!