For me, the ball that lasts the longest for playability, with longest lasting fluff is the TF1 by Tecnifibre, lasting up to 8-9 games. The Dunlop AO, ATP and Fort/Elite go soft quickly after 5-6 games and become a different ball. The Wilson US Open Select XD loses fluff and playability after 7 games.
The biggest surprise for me, which I found in Asia, is a ball called Teloon Pound, which is now ITF approved. It's a fluffy ball and softer, but stays that way for 7-8 games and is consistently "bad" in that the dropoff curve in playability is, well, consistently crappy. We opened 4 cans of 4 for our 2 2hr sessions and they lasted it with a flat dropoff curve. The QC is a bit suspect with logos misprinted and rubber seams a bit rough. Still, a more consistent playing ball than what's coming out of Thailand and Philippines.