pretty standard answer but definitely cat villagers, they just scream animal crossing to me and are one of the main reasons i have a lot of nostalgia and love for the series tbh. especially lolly, mitzi, kiki, purrl, felicity, & punchy :3c
Hard question. I adore very much both deers and wolves, but after some intense thinking I'll go with deers.
...I think I finally clarified my favourite species here. For a long time I thought I liked them just as much, but now I see that I actually prefer deers. Good to know.
I would say wolves.
I love squirrels, rabbits and cats and certain other villagers, but unfortunately, not all of them. If I had 10 cats on my island, there would be some I wouldn't like. Same for squirrels, rabbits. Only the wolves all have a cool design, so I think my choice would be them. Let's imagine an island with ten wolves... The problem is the ten personalities in the game do not each have a wolf. There is no such thing as a lazy wolf, jock, sisterly...
But their design is nice.
If there were more octopi to actually fill an entire island, I'd definitely be more interested in having just them! But as such, I feel like I have to go for penguins. They feel on theme for me and my island (especially Puck, lol) and I do like a lot of their designs.
I would probably have an all-rabbit island if I didn't have both rabbits and bovines on my island.
However, if I DID have an all-rabbit island, there's a chance that I'd name said island, "Bunland", as a reference to my first New Leaf town, called, "Funland", and the residents would be Doc, Chrissy, Francine, Sasha, Coco, Snake, Toby, Mira, Hopkins, and Carmen.