What is the best material for the ferrule?
The general consensus of opinion is Ivory. For playability, the old yellow micarta plays great...followed up pretty closely by the old paper based micarta...plays a little softer, I think. I personally like the way that Ivor-X plays, but with Kerry Zeiler's passing I don't know if they will be available anymore.
For the rest of the materials, it is pretty much a crap shoot, depending on what you like. Juma is good, Elforyn is popular, melamine (LBM), Aegis, Ivorine-4, Titan, Porper ferrules play good....there are just too many materials to list. Find a cue that hits like you like, and find out what ferrule is on it.
The tip is much more important, IMO.
Joe