Doxycycline is a good option in those who tolerate it (most people). As Df1 said, it can make you a bit sun-sensitive. It can also cause some gastritis, especially if it is taken on an empty stomach, or if you take it straight before going to bed.
I wouldn't recommend Lariam (mefloquine) in aircrew, although there is some research to indicate that in may be safe in individuals with no history of psychiatric or psychological illness, AND they have a 1 month ground trial first to ensure that they don't have reactions to it.