The Mexicans don't eat in downtown.
They eat at Tacos La Playita on Old Sonoma Road. Or Rancho Grande on Silverado Trail. Or the truck, Tacos Michoacan, which hangs out on Lincoln. Or Tacqueria La Jerazana on Jefferson.
The locals who want Mexican downtown tend to go to Taqueria Rosita on Main Street.
My favorites are not downtown, and each place does one thing better than others. La Playita on Old Sonoma is my all around favorite, and not far from downtown. Just a good, reliable taqueria, doing all of your suggestions well. Some may say Tres Hermanos, or Don Perico, downtown, but I'm not a fan of either. Wishing La Mixteca was still around.