My biggest thing is that I like to have some markings... I don't care for solid dogs, aesthetically. I also prefer color over/around the eyes.
When I got Rowan, I really liked liver Brittanys, but I'm 100% sold on orange now. I love freckles on the legs & face, but don't like orange roan at all. I like a nice clear pattern.
I think that liver roan is beautiful, but it also doesn't look like a Brittany to me.
I'm orange piebald biased, I guess
In Cardigans, I think my favorite is brindle, although honestly I like all of the colors that they come in. I especially like red brindles over brown or black brindles.
In Aussies, I like bicolors. Black, red, blue or red merle, doesn't matter, all bicolors! I *love* Cara's color and markings, although I really like minimal white, too. I strongly prefer dark reds and merles - lots of black on blue merles and rich color on reds and red merles. Sometimes the reds seem washed out and I don't care for it. This dog is gorgeous:
Solid black and bicolor GSDs used to be my preference but I'm leaning toward dark black/tan or black/red now. This is probably my ideal color:
I'm not super into BCs, but I'm a huge sucker for ee red. I've had a crush on Cobain for years and years.
I like shaded sable and clear sable in English Shepherds, although Hudson has made me like black and white, too
In K/Coolies I like both black and red in bicolor, tricolor, and with tan points. I actually like solid red too, one of the few breeds I like a solid in. (Zip Tie is basically perfection though.)
Generally I like light eyes, yellow/amber/light brown, over dark brown. I like blue eyes too. My overall favorite (outside Brittanys) tends to be liver/red/chocolate/brown (depending on breed, lol): Irish marked, piebald, tricolor, red & tan, whatever. Love it. Funny because before I got Rowan, I STRONGLY preferred black pigment, but now I want all the red dogs!