[jks]

Fraktur is still used in model theory, but I don't believe that is easier to write than A' or  or something like that.

Set theory has aleph א and beth ℶ which are refreshingly not Greek but Hebrew letters.

[jks]

Heh, U+1D504 MATHEMATICAL FRAKTUR CAPITAL A seems to have been filtered out of my comment, perhaps because it's outside the BMP.