Mio es americano, probablemente porque yo soy americana.
Mine is American, probably because I am American.
In Spanish you must say "cual es tu acento favorito en ingles"and "El mio es"
I'm native Spanish speaker but i must say that my favorite accent is American it's even harder to understand than British accent.
Thanks for the correction. Yes, American English can be hard to understand. It's almost like we have no pronunciation rules haha.