I back this 100%. I would like to add a carnitas burrito from Taqueria CancĂșn and a tofu ranchero* super burrito from Pancho Villa into the conversation.
While we are at it, I should mention that the south-west corner of Dolores Park and a can of Oly complements any of these options nicely.
I love the Veg burrito from El Buen Sabor on 18 and Guerrero