Txhunter is right. If your shots are going to be 150 yards or less then the "heavy, slow" bullet will probably be a better choice. If you're reaching out 200 yards or better a lighter, faster bullet would be the choice.

Now before anybody starts jumping up and down I know that light fast bullets are more than capable of taking game very effectively at short ranges and heavy, slow moving bullets will kill game at longer ranges. At shorter ranges, light, fast bullets are traveling faster than their optimum impact velocity. Therefor, a good deal of their energy is somewhat wasted. It doesn't get dissipated inside the animal. The bullet will pass through(sometimes causing great damage) and expend it's energy on the helpless ground on the other side. The goal is to get as much of the energy expended INSIDE the animal as possible. A lot of these light, fast bullets don't slow down to their optimum impact velocity until they get out to 200 yards or better.

At longer ranges (200 yards or more) most heavy, slow moving bullets don't retain enough energy to do the job. Also, like txhunter, said you better know the trajectory of your bullet if your going to attempt a long shot with one of these.

Either one will work, but within certain parameters. If your shots will be at varying distances(short range AND long range) then go with a light or medium weight bullet. If the majority of your shots are going to be at short range(150 yards or less) then don't waste the money and energy of the lighter, faster bullets(they tend to be more expensive). A heavier, slower bullet will probably serve you better.