Here's my take...
Ebony - high ping, crisp, a tiny bit of compression in the grind (low treble) area, quickest attack, most "modern" sounding. sweet slapper.
Maple - not as crisp on the high end, but much more forward in the low treble/grind area - strongest of the three for fingerstyle mix cutting. A bit harsh for slap solo, but works well in a mix to really come forward... may need to add a bit of control to keep it from piercing tho.
Pau Ferro - between maple and ebony is the simplest/best way to put it. I really love this material as a highly stable, well balanced tonally, pretty, and inexpensive board wood.
Application wise, for me, simplest way to put it, I love ebony best for fretless and if I'm really going for a modern tone with a really crisp ultra high. I love maple best for a J bass. great for growl and mix slashing, slap easily tamed by dropping a tone control or active treble. pau ferro for almost anything if you don't particularly want something accentuated.
And just to round things out...
Rosewood - really big warm round and mellow, smooth but present high end, great for classic tones and awesome for old school P bass. Hate it on fretless, and it won't last long there anyway.
At least IMHO/IME.