If you have a cat and get a small breed puppy, do the cats ever act as though the puppy is prey? Do they have to be separated when unsupervised? I would probably get an adult, but you never know . . . I have indoor cats, so they don't have any practical experience in hunting, but are always agog when a squirrel is outside. They have met dogs before, but only large ones.
I had 3 older housecats (7-10 yrs old) when I got my Lhasa Apso puppy and it wasn't a problem at all. They were all curious about each other, and as my puppy got older and tried to chase them, they just batted her to keep her in line. Never an injury for any of them. After 3 years, she still chases & plays with one of them, and another one of the cats protects
her from the foster dogs I get that try to bother her.
If you get an older dog, you need to make sure it doesn't have any issues with cats first. I've always found it's easier to mix them when either the cat or the dog is a baby. When they're both older they have more learned behavoir about the other and if they're hostile, they may not get over it.