
KCET's D.J. Waldie investigates the correct form of the word to describe residents of the city of Los Angeles, and decides that Angeleño is the right answer. An excerpt:
Even after the Americanization of Los Angeles (and until the early 1860s), nearly all residents of the city - Anglo and Latino both - spoke Spanish. Presumably (if it ever came up in conversation), they called themselves Angeleños, because that's the usual form of the noun.
The Oxford English Dictionary notes that the first use in print of a word denoting a resident of Los Angeles appears in California of the South, published in English in 1888. The authors of California of the South (Walter Lindley and Joseph. P. Widney) were Anglo residents of early Los Angeles writing for readers in the East. They assumed that Angeleño was the common name for Los Angeles residents.
Not Angelino or Angeleno.
The tilde disappeared as the city became less bilingual through the years. You can read the entire post on the KCET website here.