I love both of these snootys but I really can't decide between them!
I had Blaire in my WW town and my first New Leaf town, I love her design and I just think she is super cute. I love her big eyes and I can take snooty comments from her. I already have 3 other squirrels though..
Soleil: I love the hamsters anyway and she looks so pudgy and sweet. I've not really had her in my towns before so it would be completely new. I have two other hammies in my town, so I would try to plot her in line with them to have a little hamster line!
I had Blaire in the Gamecube game and thought she was pretty great, but Soleil would probably be a better choice. As has been addressed, you haven't had her before so it's a fresh and new experience.
I don't know if you time travel or if you're in the current time, but if it's the latter, Soleil's coloration seems like it would match pretty well with Autumn.
Lastly, you said you already have three squirrels. You may as well have three hamsters as well, and having a line of them sounds great.
Soleil has something off about her.... I can't tell what, but she just never fit in my towns... so I vote Blaire! she was just in my town but didn't fit the theme too well so I sadly had to let her go
I'm Blaire-biased since I have her in my town and she's one of my faves, I love her design a lot better, but if you prefer having the 3:3 ratio of squirrels to hamsters I say go for Soleil. Having 4 squirrels and 2 hamsters doesn't sound bad either though
I have Blaire in my town, she was a random move in and happened to put her house in a perfect spot. She's so sweet! She tried to move the other day but I won't let her, she's too cute and the things she says are adorable. I also have Marshal and they are always talking about each other.