this can be a real "hot button" topic, with both sides hotly debating their own views. However, I think that everybody agrees that an ounce of prevention is worth a pound of cure. What I mean is, try to reduce the instances of getting bit. Even if you're on a preventitive, it's smart to roll down your sleeves and wear long pants in the bush, especially around sunup/sundown. Use an effective repellant. Do what you need to do, including using mesh "no seeum" suits if you have to be in the bush in places and times of high risk.
Knock wood, I've never had any symptoms of malaria, although I've had locals tell me "oh, yeah, we've all got malaria". In some places on the planet, you just have to manage the risk as best you can.