I don't think I would be suited for the military in any scenario. Now, the context of the manga is indeed quite special for this sort of thing. Being within the wall, technology at best made out of steam punk wet dreams, the death of 20% of humanity over the past 5 years.... Its not the sort of world where there are many opportunities and without those the military is always a good opportunity to not starve and have a moderately stable income. I mean, imagine the kids who survived the first wall breach. The world changed dramatically overnight, parents died and the world became a more unforgiving place. Its not even about actual fulfillment anymore, its about survival. Eren and co displayed it a tad different because the military was always their goal but that will hardly be the mentality of the rest. Anyways, I don't think I am the sort of guy that would find much fulfillment in the military or serving the motherland and whatnot... Scouting legion would be out of the question for me. For me the military would be more of a step in between things, a way to move forward. The death rates at the scouting legion are for lunatics, heroes, people with a death wish (even with all the things said about being capable of making sacrifices and whatnot) and overall not suited for someone with a more long term approach to things. So that leaves the military police and stationary guard. The stationary guard does not seem to do much most of the time safe for fixing the wall and firing the cannons so it is not a particularly appealing group. Being outside the inner walls also has its issues. Moving over a larger area over more rural locations would make it easier for it to be a more permanent menial job so to speak. So that leaves the military police. They live within the wealthier district, it is a safer area and it is overall where the best opportunities might appear for a better future. Even if it does not work out that way the military police still has a better standing than the stationary guard.