Metástasis: I think this was the first show I ever watched in Spanish. I watched it when I was still in between the B1 - B2 range so a lot of it went over my head. This is an EXCELLENT show if you HAVEN'T already watched the original version from the US (Breaking Bad). I have never watched breaking bad (except for the first episode) and I can have conversations with people about the show since the Colombian version is 99.9% identical. The only real differences are: the language, locations, and actors. The names of the characters are changed for the Spanish speaking audience (Walter Blanco) for example. I believe I read somewhere that even the camera angles are the same. If you have already watched Breaking Bad, then this show probably won't do it for you. If you haven't watched it, give this show a try. A quick and dirty summary: Walter Blanco is a high school chemistry teacher. He is diagnosed with cancer and needs to make money to pay for treatment. He starts "cooking" meth using his skills in chemistry and becomes very successful. The involvement with the drug world slowly changes his personality.
Por amar sin ley: This is your standard telenovela from Mexico, but more modern. Yea, it has some drama but nothing too crazy. I think there was only one or two scenes where I rolled my eyes and shook my head. It follows the life (professional and personal), of one of the top law firms in Mexico. It has some famous actors from Mexico (and Argentina: Julián Gil). I think the Spanish in this show is REALLY easy to understand and great if you are trying to work on your listening comprehension. The slang is limited and they speak very clearly. I watched it on Univision but if you don't get that channel you can subscribe to UnivisionNOW (which I recommend) and watch it from there. I think there are a total of 87 episodes and they are making a season 2.
Dogma: This shows has 13 episodes so it's good if you don't want to dedicate yourself to a full length telenovela. The description from Univison: Un investigador de milagros es reclutado para resolver una serie de casos milagrosos e inexplicables pero su compañera de asignación no es de su gusto.
I think it was a cool show that had a good mix of action, drama, and suspense.
https://www.youtube.com/watch?v=gA1_TMJHKrYEl desconocido: This is a 5 part series on Netflix. Episodes range between 45 minutes and 1 hour. This is your typical narco novela with extra action and less drama. There is a romance involved and a lot of violence, but its an entertaining show and something you can probably stick out for 5 episodes. If you avoid narco themed shows, maybe you can give this one a try to expose yourself to some new vocabulary. Some of the show is hard to understand because they are yelling while shooting and stuff, but it's a good way to challenge yourself.
El Señor de los Cielos: This show I really liked, although I didn't actually finish it. I watched all 72 episodes of the first season and 42 episodes of the second season. I would not recommend it for your first, second, or even third television series unless you feel really good about your listening skills. This show has a lot of slang, a lot of it being narco slang that you won't even hear on the streets in el DF. This show has a lot of Mexican and Colombian Spanish. These characters are in almost every show so it's a good way to train your ears to certain actors. I noticed that after watching this show, I kept seeing the actors everywhere in other shows/movies. This was a good thing since my ear was already used to that particular actor. I credit this show with a lot of my progress I made in Spanish.
El Chema: I only watched 24 episodes of this show but will probably finish watching it some other time. Ties in with El Señor de los Cielos, and basically tells the story of El Chapo. I think it's a good show as far as action, good actors, and entertainment. I can only handle so many narco shows though so I had to stop watching it for a while.
EL Mariachi: I REALLY liked this show. It might be based on a movie of the same name but I'm not positive on that. A mariachi singer travels for some music event and gets confused for a sicario. In order to win his freedom he has to work for another cartel. He falls in love with a woman (played by one of my favorite actresses: Martha Higareda). This is a really fun show to watch with lot's of Mexican Spanish. It was on Netflix but they aren't showing it anymore. I've looked all over but I'm not sure where I can legally watch it. If they sold this show as a DVD I would buy it. I think I saw this when I was at an intermediate level and it really helped my Spanish a lot.
https://www.youtube.com/watch?v=ICIDFd5IlO8I've watched a few more shows that have already been mentioned here. I have a few more that I'm working on and hope to finish withing the near future.
**edit** Forgot to add El Mariachi