I want to buy a game (specifically Dragon Quest VIII) to use it with PCSX2, which version is emulated better? Pal or Ntsc?
Disclaimer: Naturally i got legally both PAL and NTCS bios (long story)
Im not sure for this specific game, but generally ntsc has a slight edge. And it doesnt matter which bios you have since a pal bios will play ntsc games just as good, the only thing you might need to do is use fast boot.
GamerGeek answer is absolutely correct, just want to add a bit more light on the issue.
Since the emulation is the main concern here, most games used in the tests and serving to development base are NTSC (the region plays the big role there), so they are at least theoretically less prone to errors within the emulator.
Another factor, not connected with the emulation at all but can be relevant; if cheats come into play, since they are dependent on the version and again, NTSC tends to have more. Still European sites specializes at PAL and sometimes they may have entries the other doesn't.
If you do have the choice, buy the NTSC version.