S Tier
While I don't think I paid him much thought for years in New Leaf since he just didn't fit any of my towns' themes, I saw Vic among the villager list when I was considering who I wanted to have as residents on my New Horizons island. My island is themed around world history and cultures all together in one place, so this viking bull was suddenly very interesting to me and fit the theme like a glove. His design and his house are neat and he happens to be a Cranky, which is my favorite male villager personality since Smugs no longer have the same vibe as they did in New Leaf. He's got the most distinctive, appealing design of any of the Bulls or Cows and he's just a cool guy. Love him.
Rodeo is just awesome. I love his black coloration with the gray hair and his red (now more pinkish in New Horizons) eyes. I usually tend to prefer more detailed eyes, but the red dots work for him since they kind of evoke that "creepy thing staring from the dark" vibe. I like the magic/wizard direction they went with him in New Horizons with his poster and Happy Home Paradise home request. I always liked his design, but those things kind of pushed me more into interest. I'm planning to eventually make a second New Horizons island once I think of a name, which I'm terrible at, and I plan for him to be one of the residents.
A Tier
Coach has a pretty neat design. I've never had him as a resident in any of my games so far, but I like his initial appearance with the Relay Tank. Even if he changed out of it, he'd probably still look neat with the stubble.
I don't know why, but I've always liked Naomi. I think it's probably just that, of the four Cows in New Leaf, she just looked the most distinct and interesting.
Not much to say about Petunia. Purple's my favorite color and I like her blue eyeshadow. I just like her design more than the rest of the Bulls and Cows in the lower tiers, simple as that.
I like Belle for her classic cow coloration and I prefer her over similar Tipper because I prefer the way that Belle's eyes are drawn. I wish she hadn't been dropped, but maybe the developers thought she was too generic.
B Tier
Solid enough. I like them but just not as much as the S tier and A tiers.
Not much to say about them. Oxford would probably be in C Tier if not for thefact that I had him as a resident in my GameCube town.
C Tier
They're all right.
D Tier
Jut not fond of them.
Carrot is just kinda meh. Mostly just here out of indifference keeping her from being any higher.
T-Bone's tiny, close-together eyes aren't an appealing design choice to me.
F Tier
#NotMyHolstein #Usurper #BringBackBelle
As established back when I talked about Belle in the A tier section, I prefer Belle's design as it pertains to the Holstein cow coloration. I don't particularly like her closed eyes with the eyelashes or her pink muzzle. Just overall not my thing.