It really depends on the campaign that I'm going to be running.
For instance, in the last campaign that I ran, I wanted it to be clear that the characters were larger than life heroes, far beyond mere mortals... So I gave them a staggering 48 points with which to buy their attributes.
In the next campaign that I am planning, I want to emphasize the gritty harshness of the post-apocalyptic world, so I am going to be using a 28 point buy. (I would do 25 points for this, but I am afraid that my player's would have heart attacks, going from one extreme to the other).
Later
silver