I would say one large canid is common, but more than one per zoo is unusual. Smithsonian rotates between red wolves and maned wolves (and grey?) in the same habitat, but they're only ever showing one at a time. I don't think I've been to a zoo with more than two foxes. 130+ red, 78 fennec, 60+ grey, 59 arctic, 30 bat-eared fox, 140+ grey/arctic/Mexican wolf, 92 coyote, 44 wild dog, 43 red, 30 maned, 10 black-backed jackal, 5 bush dog, 3 dhole, 3 raccoon dog, and a meager few other foxes on Zooteirliste.
Many of the bigger ones just look like grey wolves. As for the little guys, most of them are foxes/fox-like with little media presence and are harder to obtain than the red. I think that's why they are uncommon in zoos.
Favorite canid options: (don't need but would be happy to see the first 6 in DLCs if support justifies them)
- Black-backed jackal: It is unique and probably the only one I'd call mid-sized.
- Grey fox: It is taxonomically the most unique option, a cool local species, climbs trees, and would be the one I'd use most.
- Raccoon dog: It is adorable, doesn't compete with much for its region, is popular among canid options, and seems like it would sell best to me.
- Bush dog: It is the most unique in appearance and habitat among the popular options.
- Bat-eared fox: It's not a bad variety pick for foxes and is relatively common. It's also cute.
- Coyote: I'd rather get the grey fox, but it's common enough in local zoos, present in media, decently popular, and could live in all? biomes. I would buy it.
- Eurasian wolf/Golden jackal: The European players seem to kind of want a big canid. It does little for me personally, but one would be ok if support justifies it.
- South American Foxes: I kind of like the culpeo, crab eating fox, and Darwin's fox, in that order. I don't really want a DLC slot to go to them, especially not a precious South America slot, but mods would be nice. Maybe one or two could turn up in a sequel with an expanded roster?
- Tibetan Fox: funny face
- Ethiopean wolf: It's pretty and a nostagic pick perhaps worth installing a mod for.
- Red wolf: Neat conservation species and good for education. I can't tell it apart from the grey too well and sometimes forget it's its own species, but it's not bad.
To compare, there are roughly 216 tiger, 202 lion, 185 cougar, 109 jaguar, 90 cheetah, 89 leopard, 82 snow leopard, 43 clouded leopard, 170 bobcat, 116 serval, 62 Canada lynx, 60 caracal, 55 ocelot, 43 Eurasian lynx, 28 sand, 21 Pallas's, 18 fishing, 16 black footed, 13 jaguarundi, 11 Geoffroy's, and a handful of other holdings in NA.
Favorite cat options: (need the first two, maybe the third, and hope support or a big sequel might justify more someday)
- Serval: It's a favorite zoo animal of mine, super common in zoos around the world, and has a strong media presence. I badly want/sort of need it.
- Ocelot (or margay?): It's probably more important and also has a strong media presence. I kind of need this one, too. I think the margay is a more interesting alternative, but I know people would be upset with it because it is extremely rare in zoos. I'd be about as happy with the ocelot.
- Fishing cat: This would bring a tiny cat for the tropical and aquatic biome. I think they're cool and would stand in for other small tropical cats.
- Bobcat: Super common in zoos near me.
- Asian Golden Cat: Cool color morphs.
- European Wild Cat: Decent option for additional European Critter:
- Other South American Cat(s): Maybe would install a mod for one or two?
- Big Cat Subspecies: If support goes on for years and the model is way better, sure
- Iberian Lynx: I like their face and miss them a bit from ZT2.