Now, I am not going to make an argument about which version is correct (or better), but I am going to point out the differences that every writer should be mindful of when writing.
The main reason you need to be aware of the differences is because of your audience and the setting for your book. If you are writing to an American audience or your book is set in America, you want to try and avoid any British English idioms or terminology from slipping in. Consistency is the main key point when distinguishing your English version as you do not want to use favour in a sentence and then spell it favor later in the book.
Here is a short list I have put together which may be able to help you determine between which version of English you wish to use.
Every writer eventually meets them: the villain who should be terrifying… but somehow lands closer to awkward karaoke act than dark overlord. On paper, they’re . . .
Dialogue is one of those slippery beasts in fiction. Get it right and your characters breathe — they walk into a room, speak, and suddenly . . .
There comes a point — usually somewhere between draft number three and “why am I doing this to myself?” — when writing stops feeling like . . .
There’s a peculiar moment every writer knows. You open the email, or the message, or the comments. You know what’s inside. Feedback. Critique. Notes. You . . .