For me it’s gotta be “Morte e Vida Severina”/ “Severino Death and Life”. It’s an epic poem narrating the journey of a poor man from Northeastern Brazil, a famously poor and segregated region that’s frequently affected by severe droughts, fleeing from his home and walking to the big city to survive the season. On the way he describes all the misery he experiences and sees.
One stanza that has stuck with me for years goes something like this "And all of us Severinos/With the same lives/Will die of the same/Severe Severino death,/The death died of/Old age before thirty/Of an ambush before twenty/And of hunger day by day/(Of weakness and plague/The Severino death/attacks at all ages/even those not born)
Martín Fierro. It is a (very long) epic poem about the life and times of one gaucho in rural and frontier Argentina. Beautifully written, with exquisite attention to rhyme, perfect use of local expressions, it also doesn’t pass upon oportunities to make social commentaries on the life and times of the characters.
The only downside is that you have to know Spanish in order to fully appreciate it. There are several very good translations that are faithful to the tone and the intention of the author, but the rhymes are invariably lost.