I stand by Fassi's rice and Fior di Luna's pine nut, but my time here in Rome has taught me that there is always a better cup of gelato waiting around the bend. So that you may experience joy, I have slogged through many different offerings of varying quality and have emerged with these recommendations:
Fatamorgana makes innovative flavors with meticulously sourced ingredients (all natural). The flavors change seasonally, but I last had a gelato di zucca (squash) that was intensely squashy and not too sweet. It had toasted pumpkin seeds in it, which I think we can all agree is an awesome detail. I go to the location in Monti on the Piazza degli Zingari.
I Caruso makes the object of my current obsession: fig gelato. I've never eaten an ice cream that so completely evokes the fruit, split open and glistening in my hands, filling my mouth and nose with its perfume and soft pulp. This is a gelato to beat all others. It captures the texture of a ripe fig, not just the flavor. They only make around ten flavors regularly, in addition to changing monthly and weekly flavors. Last week they had pear gelato that was similarly out of this world perfect, down to the slight graininess of a pear's flesh. The classic flavors are also potent and wonderful, particularly the gianduia (chocolate hazelnut) and pistacchio. Find it at Via Collina, 13-15, close to the Repubblica metro stop, amidst the glamorous palazzi of the financial district.
Gelateria del Teatro is another good choice for a lovely pistacchio, and their more innovative flavors can be great. I had a ricotta, raspberry and sage gelato that was fluffy, sweet and aromatic all at once, delivering on the promised flavors. On the other hand, there was barely any fig flavor in the fig and honey gelato (thank goodness I've found a reliable source). Via di San Simone, 70.
I will continue to seek ever more delicious gelato for you, dear readers. It is a thankless and miserable task, but lucky for you I'm just that selfless.