Crowsnest,
I started a thread on Rotorheads asking if Exxon wee violting my human rights by forcing me to take anti-malarial tablets. There is a lot of information on that thread about the various anti-malarials, especially from RD Rickster.
The most effective prophylaxis basically depends on which part of the world you are visiting as there are different strains of malaria in different areas and you have to take the prophylaxis most suitable to the area you are to visit.
I only object t having to take them long-term and have no doubt as to their effectiveness. Here in West Africa, the most common form of malaria is Falciparum Malaria. This is also the deadliest and fastest acting. Malaraone is very effective, but expensive, and has nasty side effects in a lot of people (mostly heartburn and mouth ulcers). These would probably not be serious enough to affect your performance on the Flight Deck. Larium is very effective but many airlines, such as my own, ban its use by flight crew because of the possible mental disorders. The other effective pophylaxis is Doxycycline, the main side-effect of which is to make you more prone to sunburn if you are light-skinned. If you are woman it may also mak you more liable to contract 'thrush'.
Hope that helps. Check RD Rickster's links which give a lot of valuable information.