Which Aero to keep

Hi guys,

Was wondering if there are any good article to read up on Dragon Fish. Which is the most popular species and also which is the most expensive. I heard that red is ex. but I also heard thtat cross backs are solid ... how do you guys tell which is which anyway, or do we just trust the sellers? How to choose. I seen some spoon shaped ones and some people say they are more expensive, but I think they do nto look good. I rather the normal looking ones. Also, soem say a shorter body and thicker body is the right fish to keep ... is it? Is there any standards? Cheers.