I know I'm a little late, but in case anyone else reads this thread and wants recommendations, here are my thoughts.
I've eaten at Venda and they are really good, but I didn't eat pizza there. Actually, I didn't even know they made pizza.
My recommendation would be the grilled pizza at Bob & Timmy's on Federal Hill (one of the side streets). Grilled pizza didn't sound that appetizing to me when I first heard about it, but it is really good. Al Forno's in downtown Providence (really close to the Hill) originated the style. They are kind of like Chez Panisse in California in that they are both high-end restaurants known for their pizzas, but Bob & Timmy's just serves pizza.
Caserta's is really popular in RI, but I absolutely hated it. It reminds me of the pizza they used to serve you in grammar school. It is actually baked on big aluminium sheet pans just like the cafeteria lady did back in grammar school. However, their Whimpy Skimpy is pretty good. It is a spinach pie (calzone) and is another food item Rhode Islanders enjoy (I agree with them on this one).
Palmieri's on Federal Hill is especially well known for their pizza strips. This is kind of a slice of Sicilian pizza that has sauce, some sprinkled on cheese (I believe Romano), and is served cold. It is the baked bread that is the focus of this pizza. Once again, these pizza strips are really popular in RI, but I don't care for them. Although most Rhode Islanders seem to rave about Palmieri's pizza strips, I think Scialo Bros. Bakery on the Hill is a much better baker. They have a massive brick oven that is about 100 years old (founded 1916) and they have some really good food. I haven't tried their pizza strips, but I know they make them.
There are a couple of other pizza joints on Federal Hill, but none of them are especially well respected. They're just places that pop up and then disappear when they get replaced by something else a year or two later. There is a place called Sicilia's on Federal Hill that makes a Chicago style pizza and it gets decent reviews, but once again, I didn't care for it. Where the bread and toppings meet the bread turned gummy. That just ain't right. Plus, who goes to Providence for Chicago style pizza?