Even though I built the classic police station because it first my town better, I think Copper is wayyy cuter. Something about how serious he is despite being a doggy in a cutesy game just makes him so silly and adorable.
I've only had Booker in a few towns so far. His fumbling and mumbling was entertaining for a while but that's grown stale and irritating now. The next station will be modern because variety is more ... well, more. I've only seen Copper in his RV but I liked the contrast with Booker and will give him a try.
I prefer Copper. He is serious, yet sweet and nice. Plus he's cute. He's also the first of the police dogs I ever interacted with, so I have the nostalgia aspect with him as well.
I would choose Copper, because of his personality. But he is in the modern police station, I like the Classic one more. Booker is ok, but i'm going with Copper here. I just kinda wished you could have the choice which one you wanted in your police station.
I think that originally I liked Copper more because I found him aesthetically pleasing-- But I really like how timid poor Booker is. I want to take him home and cuddle him c: I mean, he gives you the same information copper does, he's just all nervous about it-- I kinda identify with him in that aspect I guess ╮(─▽─)╭