I'm not sure if English is your first language but the correct wording is "Who's prettier" or "Who's more beautiful". But if it's more than two people it's "Who's the prettiest" or "Who's more beautiful" and you only need to use one question mark (but this part is optional). I'm not trying to sound like a nag, I'm just trying to help.

Anyway I think Kristen is gorgeous, when she's not smoking and making herself look like a stoner.

I think Kristen is prettier

Ashley is gorgeous, Kristen is beautiful, and Nikki is pretty.

And Nikki.
Kristen is plain.

Something about her I just love. Ashley too.