If you could pick your species...

I actually really like my kintypes. I don't think I would change them. Being a wolf is sort of the basis of my entire identity. And, for the most part, I love being a gryphon. Even the kitsune has grown on me to the point that I wouldn't change it.

If I had to change, though, I'm going to answer this as a sort of "change each kintype" sort of deal. I have two wolf theriotypes: a Canadian timber wolf and an African golden wolf. If I had to change them, I think I would choose a snow leopard and a carrion crow. Snow leopards are actually very similar to my gryphon kintype. Their build, with the low-slung body, big paws, and extremely long, thick tail fits my gryphon almost exactly. The fur is different, in that it isn't designed to be water repellant, but it's still very thick. The climate in which they live is not terribly unlike my timber wolf. The landscape is different, but the climate really isn't all that much. As to the crow, carrion crows are pretty much your standard crows you see everywhere in Eastern North America. They're also quite intelligent. I'm crowkith and I've felt deeply connected to them my whole life. I've often wished I could be a crow. So if I had to change from my wolves, I would be a crow.

I also have two kintypes: a coastal gryphon and a kiko kawa kitsune. There is... a whole lot of water going on there. My gryphon self lived on the shore of an ocean and the "kawa" part of my kitsune classification denotes that I was a river elemental. So much water. If I had to change them, though, my first thought was "dragon." I do often wish I was a dragon rather than a gryphon. You can't turn around in a 'kin space without tripping over dragons, but I've never met another gryphon. I've looked, and I've talked to folks who've met others, but I've not found any. Which is sort of lonely. But I'd want to be some sort of dragon with a connection of some kind to water. As to what I would choose in place of my kitsune if I had to, I would choose a black dog - a creature from the folklore of the Brittish Isles.
Specifically, a gytrash. Gytrash are a type of spirit that haunts lonely roads. They can appear as huge, black dogs, but also as horses, mules, cranes, and according to some lore, even cows. They often mislead travelers, but they do sometimes act benevolently and guide lost travelers back to the correct road. I find black dog lore fascinating and the gytrash has always been my favorite. Also, it's a shapeshifter and a trickster, like my kitsune, although not in the same capacity on either count. And it's a spirit creature. The "kiko" in my classification denotes that I was a spirit fox no longer bound to the physical plane. So that fits as well. So really, if I had to change from my kitsune, I'd be a gytrash.