I think a Unicorn & a Zebra would actually be a great match! as they both look really different to horses & can relate!
Savannah has stripes &
Julian has a horn, they both look different! If being different is important to you, Julian is a magical creature, so that certainly wins IMO.
I am also biased against Colton, because in my town he acts like a shallow jerk. I've never had Julian in my town, so I don't know.
I have had
Roscoe, and if you want a cool black horse with a heart of gold & don't mind the intense eyes, you may even consider him.
But you know you don't have to have the same species date.
I know it's weird, but new leaf doesn't seem to follow any rules like that.
e.g. Muffy has a crush on both Lobo & Freya....
Boomer is a unique looking male penguin. He dresses like a pilot.
Tex is also a good choice, lots of people seem to like him, but he's still not a top tier, so he's unique enough.
if you don't care about the gender,
Sprinkle would be a cute, peppy (literally!) match.
As far as the Ostriches, there is only one male, and for some reason Phil doesn't fit in my mind for what you are after. I'd say just expand into the other types of birds.
Males I would recommend are:
Keaton (smug eagle, beach themed house, light blue & yellow feathers),
Lucha (really unique smug bird, Lucha wrestler.
I hope this helped!