Thanks KC for the clarification on your interests and budget. I will outline some of my favorites in the city. I am from the SF Bay Area, living 45 minutes from the City and go quite often.
Italian
For restaurants outside of North Beach my two favorites are (1) Seven Hills in Russian Hill is a farm-to-table Italian restaurant that is family run. Everything on the menu is amazing, the standouts are their house made pastas which are ~$30 and are large enough to share. (2) A16 in the Marina which has wood fired pizza’s excellent pastas and the best meatballs I have ever had, my husband hates meatballs and he loves these. The bonus of this area is that you are a short walk from the Marina and the Palace of Fine Arts, same price range as Seven Hills. (3) Flour & Water in the Mission, amazing pasta and pizza, very small and books early. A few minutes from Flour & Water is TrickDog an inventive cocktail bar with literary references.
In North Beach, so many great options, in fact, I have curated my own food tour from Chinatown to North Beach, DM me if you want me to send you a copy. Tony’s Pizza Napoletana run by the 13 time world Pizza champion. Pizza’s range from $29-38. Long lines, but absolutely worth the wait. Across from Tony’s is another Italian fixture, Original Joe’s. If you are in the mood for Cioppino, Sotto Mare in North Beach has the best in the City. Entrees range from $30 to $58 for the Cioppino. Also in North Beach is Molinari’s for amazing sandwiches and you can walk a few minutes to Washington Square Park to eat. In North Beach, we always go the cash only Cafe Trieste which was the first espresso coffee house on the west coast. If you are interested in a Comedy show, Cobbs is in North Beach, also City Lights Bookstore, home of the beat poets is in the same neighborhood as these restaurants.
Mexican + Bonus Recommendations
The best Mexican restaurants besides Californios (which is very expensive) are located in the Mission. A few of my favorites are Taqueria El Farolito which is a Mission institution and is very reasonable $10-$20, it is cash only. I also love Lolo which is a family owned Jaliscan restaurant with really inventive tapas. I love their ceviche, Spicy shrimp tacos with tropical relish service on jicama shells. They also have a great Tequila and Mescal selection, ranges you can eat well here for around $100. If you are in the Mission and want amazing bread, sandwiches and pastry, Tartine is the place to go. Also near Dolores Park is Bi-Rite Creamery, amazing ice cream, my favorite is the Snickerdoodle.
Asian
There are some amazing places in Chinatown, my favorite is Good Mong Kok for Dim Sum. They are take out only, but if you want to picnic, this is a great spot. Four Kings is legendary, but hard to get a reservation and a bit pricey. If you want an amazing wonton noodle soup, Hon’s Wun-Tun House is a walk-in only place that has been around for 40 years.
My favorite dim sum and Asian restaurants are on Clement street in the Outer Richmond. My favorite Dim Sum again is another take-out Good Luck Dim Sum also on Clement is Wing Lee Bakery. For something other than Chinese, you can try Burma SuperStar on Clement. I have been going here for more than 20 years. My favorite thing is the Tea Leaf Salad and the Burmese Curry. It is around ~$20-$30 per entree and everything is shareable.
Bonus: Tunnel Tops Park in the Presido is one of the best National Parks with stunning views of the Golden Gate Bridge. They have a restaurant Il Parco that has sandwiches, salads that you can eat in a patio area or take to go and sit in the Adirondack chairs in the park looking at the Golden Gate. Also, there is a new food hall that has opened up recently in Presido which is next to the Tunnel Tops, it is getting rave reviews and if you want a few upscale fusion restaurant, Dalida is a good choice.