NTSC-U = USA/Canadian.
PAL = European/Pakistani.
NTSC-J = Japanese.
Best is NTSC-U (99.9% games released work on it), and very very close to it is the PAL (99.5%) one, but NTSC-J (can't say, but I know) is somewhat little behind them both. Remember that you'll need to buy a 110v converter or stabilizer for the NTSC-U one to work.
This happens because games are region locked.
Some games are region free and will work on all the three region consoles, but some games, like Cricket games work on some consoles and not on the others.