There is always a lot of discussion about the amount of deflection on different cues.
Platinum Billiards have developed a test to measure deflection and displays their results in a deflection ratings chart.
New additions are still being made., but right now the three Predator models (Z, 314 and Break), McDermott i-3 and Universal SmartShaft lead the way so far. They have been given a deflection rating of "low".
The tests are performed using a robot, which makes the same stroke with each cue. Four shots are made, with varying distances from the center. It's the average for this series that determines the ratings.
Platinum Billiards claim to be an independent company with no affiliation with any billiard product manufacturer.
See the newsgroup thread "Platinum Billiards' deflection chart" for a general discussion.