What Type Of Dog Should I Get?

My parents have decided to let my sister and I get a dog! =) We’re both teenages and would prefer a small to medium-sized dog, not like a retriever-sized, but not a tiny Paris-Hilton type.
I’d like to have a breed that’s friendly, caring, playful, loving, loyal.. and basically all the great qualities of a dog. I really like Cockapoos, but what’s the best kind of them to get, and are there any other good breeds you recommend?
One more thing.. would yolu recommend getting a full-grown dog or a 1-year old puppy or something? We’d want it to be little when we get it, but trained…
All answers welcome =)

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