Over 28 years flying in West Africa now and I've been lucky enough never to have had malaria as yet. When I first came out here I took the old chloroquine and nivaquine, which are now almost completely useless. I took no prophylaxis for many years, but always kept whatever the latest treatment was in case of emergency for self-treatment (from quinine sulphate to Halfan to Malarone as newer treatments were found). When I was working in Cameroun our client oil company insisted that we take anti-malaria prophylaxis and i took Malarone for a few months, but then gave it up when it gave me problems with stomach acid, mouth ulcers, headaches and eyesight problems. I took doxy for about 6 months with no problems except being more prone to sunburn.
I'm now back in Nigeria and I take nothing, but as some people here have said already, I take precautions to try and avoid getting bitten, For my emergency treatment I carry Coartem (artemether and lumefantrin) which is currently the drug of choice in this part of Africa. Artemether, combined with other anti-malarials currently seems to be the most effective treatment (though that will doubtless change).
Most doctors in Africa will know what the best drug is for their part of the continent (provided it's available to them) and many of the better hospitals and clinics can get a blood test result in a very short time to determine whether you do have malarial parasites in your blood and which strain you have.