Both aerobic and anaerobic respiration yield a net gain of atp molecules to be used as energy for living things. the processes of would yield the highest number of atp.

     Well, for this answer what you need to have in mind is how the process of making ATP works and where it happens.

      It's a very complex process, there are three of them that occur in and out of the mithocondria. The first one happens outside of it, but the other two happen inside of it. These three processes are called glycolysisn, krebs scycle and  oxidative phosphorylation. The process that produces more ATP in all of these three is the oxidative phosphorylation, but be careful, they are all linked to each other, so the understanding of the whole process is the main thing you need to know to answer this question. Hope it's helpful!