This is a difficult to answer question, you might say each land has different values and ideals, you can read the signpost at the gates of the land or talk to people from that land what the land is about and try to enter the land you resonate the most with.
a word of warning, MD is a living game there is also a history the lands or people of the lands have with each other and thus might not speak well about some of the lands they are not part of
if you join a certain alliance you will automatically gain citizenship in the land the alliance is part of, but you do not need to be in an alliance to enter a land as citizen