Agreed, this is easily my favourite US state flag. It's super unique among the 50 flags and is also satisfying to look at.
In regard to my country...
Mexico's states have
coats of arms rather than flags due to the legacy of the Spanish colonization, with only 14 of the 32 states (if we count
Mexico City as one) having an
official flag. Even so, most of those flags are merely the state's coat of arms displayed on a background, which is a plain white in the worst cases.
Thus, my favourite state flag from my country is
Yucatán's, since there's not much to choose from:
This flag's origin lies on the fact that Yucatán wasn't always a Mexican state:
Founded on May 29th, 1823, the
Federated Republic of Yucatán was an independent state until it joined the
First Mexican Republic on December 23rd, 1823. It lasted less than a year!
In 1840, the state declared independence from the
Centralist Republic of Mexico and adopted the name of the
Republic of Yucatán, alongside that flag. 8 years later (during the
Second Federal Republic of Mexico's period), it rejoined the country for good.