now this may sound stupid and i guess i have my own view because of personal experiences, I love mutts!
I grew up around a mutt, from what every one guessed she had lab in her with the ears and so on. With her white coat she was so cute.
Later in life my sisters and i moved away, I got a cat, one of my sisters got a boxer, and the others got mutts.
I can say, you will love whatever dog you get and of course its a crap shoot with a mutt. Purebreds are expensive, and vet bills can go through the roof with genetic problems with a breed (ie: hips with German shepherds)
Even though we had a mutt growing up, she had very bad heart worms and it cost ALOT to save her. She was young so she survived and lived for about 15 years!
There are NO for sures, just best guesses.
Learn how to train your dog, nothing worse then an untrained dog

Good luck!