I've come to feel the best attribute is "Accurate." I don't have any accurate distance drivers yet, level 32 now.
Bag:
Pure: Accurate, Sticky (Sticky seems extremely important for catching chains on slightly errant throw-ins)
Compass: Accurate, Heavy (This one is for the 'tweeners, gets plenty of use as a straight brick)
Explorer: Accurate, Extra Glide (The workhorse of the bag, very diverse because of its accuracy at distance)
Musket: Accurate, Big Skip (Just trying this out, flex slot and open to suggestion!)
Ballista: Light, Big Skip (High variance, but makes me lots of eagles along with OBs)
Ballista: Wind Break, Extra Fade (Surprisingly accurate, but not often that useful)
What I want:
Any "Accurate" Ballista. Extra Glide, Wind Break, or Heavy would probably be fine paired with "Accurate."
An "Accurate" and "Big Skip" Ballista for the insane things it would do.