Recently went out to try different balls and here are my findings best to worst:
Dunlop Championship All Court
Playability is very good. It is a lively yet durable ball which is easy on the arms. Very consistent bounce and good visibility. Still has life after 6 x 2 hour sessions with medium to hard strokes.
Dunlop Grand Prix XD
Playability is good. It is less lively than the Championship All Court balls and is heavier and harder on the arm. It is however slightly more durable than the Championship balls though. Good visibility and consistent bounce. It does fluff up a bit but not so much to affect play.
Wilson US Opens
Playability is good with a bounce similar to the Grand Prix. Slightly less heavier and harder than the Grand Prix but more so the Championship balls. Less durable than either other Dunlops with most of its felt being worn away much quicker.
Wilson Titaniums
Playability is good with a very lively bounce. However durability is poor with its felt coming off very quickly.
Penn ATP Professional Extra Duty
This ball is very similar to the Grand Prix ball being a bit heavy and hard feeling with similar durability.
From a cost point of view, the US Open and the Penn ATP balls are the most expensive at ~$4.99 per 3 ball tin (Vancouver, B.C.). Both Dunlop balls at my local Wal Mart is very reasonable at $1 per ball in their respective 3-ball and 4-ball tins. I prefer the Dunlop Championship balls for its superior playability over the Grand Prix's superior durability. Hope this helps. Cheers!