The ‘multiple airline’ sites DO NOT necessarily offer the lowest fare despite their claims. I will be taking a long haul flight in April and I have been monitoring every website that has been created since the savings can be in the $ hundreds. Lowest airfare - the airline’s own site consistantly for two months now.
Also I have noticed a trick that is used of quoting a low, low airfare but adding unitemized ‘fees and taxes’ that bring it back up to the level of all the other sites. Maybe there are intermediate layovers/stopovers that attract extra taxes but it seems fishy to me.
Caveat emptor!
I am a Travel Agent and the sites always list the fares before taxes and fees. Those are all added once you click purchase and then they will also add a service fee just because your using their site.