The Yado Kingdom

Population: 10,900

Deffenitely the most dangerous. Its in control of the biggest land, and the villages are thriving yet fearful.
Crime rate is very small in these Kingdoms due to the excessive amount of guards patrolling the area.
The Kingdoms are always at war with the next biggest kingdom to try and overrun it, or at least get some land from it.
The easiest employment (and most popular) would be becoming a page when your younger and advancing to a squire and then a knight or guard. Gaining reputation from wars would come easily because, well, theres a lot of them and theres high demand for guards even if there's already tons of them.

The Druiweth Empire

Population: 2,500

Its the smallest Kingdom, there are little to no recognizable nobles and even the palace isn't very big nor grand. Because of its lack of villagers, most of the land is empty for farming.
Crime rate is non-existent in these Kingdoms due to never being in wars theres tons of guards waiting for anything to happen, so criminals travel to either the Yado Kingdom or the Umonian Kingdom.
The Kingdoms never get into wars and are always the first to retreat -- If they can give them the land its even better, as the smaller they are the less the Yado Kingdom wants anything to do with them.

The Umoneian Kingdom

Population: 5,450

This Kingdom is moderately sized, and always at war. Being much larger then the Druiweth Kingdom the Yado Kingdom wants everything to do with them, and is constantly fighting them for their land.
Crime rate is exceptionally high since there are very little guards to protect the citizens since they're all off at war.
The best job idea here would be a thief. Despite the high demand for knights, nobody wants to become one considering it might as well be suicide.