I like Guaymas, it's very authentic, there is good value for your money, and it's a very good representation of taqueria food that you might find closer to the Mexican border. However, I find it to be a bit lacking compared to the excellent service, and far better food at El Rinconcito (I think I spelled that correctly) in Tukwila. Although Guaymas has one thing over Rinconcito, it's usually fairly quiet. Rinconcito used to have a small bar in one side of it, and it became a hangout of sorts, and the sound of Spanish language TV combined with the sound of the jukebox got a bit loud. But it can sometimes add to the experience, providing a relaxed atmosphere while dining. Guaymas is my second choice for best taqueria.
Pros: Decent food, Good prices
Cons: employee attitude