which has better PQ/AQ?
PQ and SQ are the same.
Overall which one do you prefer?
I prefer the US version.
If you are very particular about frame rates, the Region A version would be better.
Special features are sometimes in SD format. If it's a Region A, the SD features will be in NTSC format; if it's a Region B, the SD features will be in PAL format. The PAL format's 25fps causes a slight speed-up.
Of course, the main movie will be in HD format. If it's a Region A, the frame rate is usually at 23.976 fps (sometimes at true 24fps); but if it's a Region B, the frame rate can sometimes be at 25fps. A frame rate of 25fps will cause a slight speed-up.
http://www.avsforum.com/avs-vb/showthread.php?t=1117941===================
You're going to hear this a lot ---- "PAL and NTSC are no longer relevant to Blu-ray".
If anybody tells you that, don't listen. He doesn't know what he's talking about.
Why NTSC and PAL Still Matter With HDTVHow Digital TV and HDTV Are Linked to Analog Television Standards
By Robert Silva, About.com Guide
A lot (of) consumers around the World assume that, with the introduction of Digital TV and HDTV, the old barriers to a universal video standard have been removed. However, this is an incorrect assumption. Despite the fact that video is going digital, the fundamental difference between video standards that exist currently, Frame Rate, is still the foundation of the new Digital TV and HDTV standards. ...
... In the final analysis, Digital TV and HDTV, although a leap forward in technology implementation, in terms of what you actually see on the screen, with reference to increased resolution and detail, still has roots in 50-plus year-old analog video standards. As a result, there are, and will be, for the foreseeable future, differences in Digital TV and HDTV standards in use throughout the World, which reinforces the barrier to true Worldwide video standards for both the professional and the consumer. http://hometheater.about.com/od/televisionbasics/qt/ntscpalframes.htm