In Anaheim Pizza X at Brewery X.
Other favorites of mine are:
Loosie's Pizza in Santa Ana (NY style)
Pietrini Pizza in Los Alamitos (Neapolitan)
Riip Beer & Pizzeria in Huntington Beach (Detroit & NY style)
Folks Pizzeria in Costa Mesa (thicker crust + naturally leavened)
Prince Street Pizza in Costa Mesa (Sicilian squares & NY style)