I have tried Tehzeeb, Rahat, Domino, Pizza Hut, Pizzario, Italian Pizza, Blue Castle, Pappasallis, and many other and I suggest in Lahore, Karachi and Islamabad as per my experience.
I tried Blue Castle, Dominos and Pizza Hut in Lahore and I think Blue Castle tasted good.
While in Islamabad Los Angeles pizza is at number one position as per my taste standards due to their thin crust and filled stuff and original recipes, and imported chillies & sauces. I think los angeles pizza is the best pizza in Islamabad.
14th street pizza is at number 2 in Islamabad
While in Karachi I vote 14th Pizza as number one.