Honestly even though I love all the wolves in this game, i'd sadly have to say it's not a very hard decision to make for me, and my choice of islander to evict would be Audie.
She was probably the first villager I got that I actually liked, and at first I really did like her. I'd read the story about the old grandma that played new leaf for 2000+ hours called audrey, and the fan theory that Audie was named after her. I also paired her up with Dobie on my island once I managed to get him (which was pretty quickly after getting Audie if I remember correctly) to be my in game grandparent's, since I loved the idea and also love pairing villagers up with others in relationships. However after a while I kind of just came to the realisation that I didn't like her. I mean, I never really attempted or tried to interact with her after the first week I got her, while I was still talking to all my other villagers on the daily. I also never gave her gifts or decorated her yard nicely, and found that she just didn't match up with my expectations. To be fair to her though, I really just don't like the peppy personality type in general, and would be perfectly happy to not have any on my island. For now though, I need someone to keep Dobie company in his old age so he doesn't go senile, so she can stay until I finally fall in love with another villager and am forced to move her out.