I have both a Yorkie & a Maltese and you can't really go wrong with either. It is just a matter of personal taste. You really need to spend some time with both breeds to see what suits you best. My Maltese is a little more sure of himself than my Yorkie. The Yorkie tends to have a little more nervous temperament and is more difficult to train. The Maltese seems more like he wants to please me and the Yorkie seems to think she is training me to please her. They are both precious dogs & you will love them.
As to the Morkie mix, I wouldn't purchase one -not because I don't think it wouldn't be a wonderful pet. I'm sure it would be darling. I just don't believe we need to encourage indiscriminate breeding of pets. Now if you could rescue one, that would be great. Honestly, I think all of our pets should be neutered unless they are champion material. Good luck on your new addition.