Hyenas. Really bad. I would have loved to have a hyena pet, but I can't get past the incredibly blocky, pixelly models they have.
Original wolves could use one too, for the same reasons, but I guess the worgs and saberworgs kind of count? One of the reasons I'm really not after Karoma. The spirit skin is kinda neat, but yech, old wolf model. Give me a ghostly sabreworg and I would be ALL over that. Skoll is still one of my favorite models.
Agreeing with bats as well. Bats are actually my favorite animal of all, yet I never felt inclined to tame one due to the weird looking models.
Pretty much all the old cats too. I'm echoing that they all not need look like Sambas, they just could use a higher polygon counts and higher res skins. That goes for all vanilla tamable though, really. Even though, in game, I think Sambas' model is reaaaaallly nice looking, I would be mighty peeved if all my hunting was suddenly made pointless.
And these ones aren't all that old, but I still think they could use a leeeetttle work:
Foxes. Why is a fox twice the size as an undead or blood elf? The models they have are nice, but they are just so dang BIG.
Demon Dogs: And in contrast, these seem like they would be a lot bigger when tamed, instead it's not that much bigger than my hoof. It's like a demon chihuahua. I LOVE the models, especially the runed variants, but I wish they were a little more beastly in size.
Loque: That face. THAT FACE. That is all.
...But honestly, I would take a nice upgrade to PLAYER MODELS over NPCs first. Look at how nice looking the worgen and goblins look!
Krakatoa - Orthus - Stein - Maahes - Bowser
Skade - Server: Elune - 85 Beast Mastery/Survival Hunter - Guild: Wardemons
FOR THE HORDE!