I'd personally choose hazel! shes so darn cute and such a lovely villager to chat with <3 id happily take time out of my day to chat with her about anything and everything! I also think she'd work well with your foresty theme since she just has that look
Filbert is my favorite squirrel mainly because he's the only one I've ever had. But he has the same personality as one of my dreamies, so that kinda stinks of I end up getting him :/
I have Nibbles too, I don't want her in my town so once she pings to move out, anyone can have her. it's gonna take awhile though... -.-
Nibbles is an adorable Peppy! She has a cheerful house. Very cute.
Pecan is a lovely sophisticated Snooty. Her roof is purple and looks great with pine trees on the north part of town.
Marshal? If you need a smug he's one of the best as you probably know. But his house is so modern looking. I'm actually considering finding another smug because his house sticks out too much in my forest town.
Mint is another wonderful Snooty. Her house is green so depending on your color scheme it may be great for you.
Sylvana is a perfect squirrel for a forest town! If you can get her she is a must have!
Good luck coming on all your choices! Wishing you all the best!