Very difficult to answer this without knowing where you work, where you go after work, how much you plan to spend on rent, etc.
Wan Chai - a red light district. Star Street area is ok but lots of bars.
North Point - much more local in comparison.
Kennedy Town - new MTR, new western restaurants.
If you're mentioning North Point, you probably want to save money and not too concerned about timing to work, so North Point is likely to be the cheapest. Just remember you get what you pay for and there is no such thing as a good deal. If it's cheaper, there's a reason. When you let yourself get greedy, then you will be back here in 6 months complaining about the million things that can go wrong and what your options are, and let us tell you now, NO options once you sign.