I come from California, so I've had my fair share of excellent Mexican food, and Taqueria Guadalajara is definitely on par with some of the best Mexican food I've had.
My favorite item here is straightforward: steak tacos. Fresh, soft corn tortillas packed with fresh seasoned steak, onions, cilantro, and lime. It's heaven, plain and simple. Their other meats are of course excellent as well, chicken and chorizo are my other favorites, but seriously, I wouldn't mind only eating their steak tacos for the rest of my life. Would also recommend a horchata to go along with your meal. Many places in California are guilty of diluting their horchatas, but not in Wisconsin!
Ever since finding out about this place, I now go every week, usually twice when I'm desperate, and always sit at the counter. Always amazing service, and amazing food. Will continue to go here every week while I'm in Madison.