Choose SER (SOY = I’m /ERES = you’re /ES = she’s) if you are going to use adjectives which describe inherent personality traits or characteristics of people or things. i.e. English, Spanish, intelligent, silly, short , tall, etc.
We live in an era where there is no doubt that equality of the sexes is an important issue and is to be striven for. Why has this not filtered into grammar yet?