Etoile is such an adorable new village, oh my gosh! But, I would definitely pick Stella given he reasons that you provided. I think she can find a nice spot in your heart to fill if you will let her. I love the sheep villagers. They're all so squishy.
I pick Stella because from what information you told us about I think she will go great since you like her and got excited when she was going to be in the update.
Being an ?tolie fan, I would say you should keep her. In my opinion, she is one of the most aestheticaly pleasing out of the bunch. Her furniture is cute, too.