I personally have 2 dogs TS-- a mix breed (shih tzu - chihuahua) and a pure breed (shih tzu). I got the mix breed first then after 2 months got the pure breed... I treat them fairly although mas ni come out pa na mas-sweet and affectionate ang mixed breed. If i am sad and i cry, she would always lick on my tears and dry it out. If i am sick, both of them do not eat as well and would stay by my side on the bed...
So it does not matter gyud TS if mixed or pure. Although if you wish to join prestigious competitions or shows gyud,it has to be pure breed gyud. Pero if pet lang, it would not make a pure breed more of a pet than the mixed and vice versa.
If first timer ka TS, first things first know what you want, make a little research. And put in mind na a dog's behavior will depend on how it's owner trains him.
Just my 2 cents TS