The place that everyone recommended to me was Can Paixano. It's not traditional Spanish tapas, but if you're looking for authentic Catalan, it's the place.

I had great tapas, including a hamburguesa caballo, at Bar del Pi just off La Rambla.

Finally, I had a great tapas breakfast at Cervecería Catalana.

Hope this helps!

Edit: I only put tapas places! For sangria, try El Bosc de les Fades, the most interesting bar I've ever been to.

I'm sure you are going to get a million answers to this question, because Barcelona is full of incredible tapas places.

I consider myself a bit of a tapas snob, and my personal favorites are:

Tapas 24 - http://www.carlesabellan.com/restaurantes-tapas-24/

El Vaso de Oro - http://vasodeoro.com/

Also, in the back of the La Boqueria there are a lot of tiny little tapas bars, and they are all pretty incredible. One of the best, and more expensive, is El Quim, but it's worth it. It's rumored that El Quim is where Barcelona chefs go see what is in season and the latest food trends. It's amazing!

SO MANY TAPAS! It's quite hard to go wrong -- at least as someone who grew up nowhere near a tapas culture. From my tapas-free childhood, the lines upon lines of tapas deliciousness were like presents waiting for me at dusk, every day. Some of my favourites below:

Bar Pinotxo (La Rambla 89) just outside the entrance to La Boqueria. Order the chickpeas and order the fried artichokes. Trust me. Eggs and clams are good too. DO NOT GET THE CUTTLEFISH. (With all due respect to cuttlefish lovers, this was not my fave.) 

El Quim de la Boqueria, mentioned elsewhere in these answers. Order the "huevos con setas y foie" (mushrooms topped with foie gras and sunny side up fried eggs), and anything else. A bit more expensive but quite worth the price, imho!

 Euskal Etxea Taberna - pintxos, all of 'em, 'specially the hot ones. 

 Tasca el Corral - for some reason address doesn't load on Trippy map, but its place page is here. Order the chorizo al diablo (flaming chorizo with agua ardiente), Manchego cheese, and if you like cider, they've got decent cider choices on their menu.

Bar Celta Pulpería for Galician style tapas, specifically incredibly delicious octopus and other fun fried goods.

Cervecería Catalana - try the huevos cabreados (fried potato with spicy sauce and eggs), broqueta de gambas (shrimp skewers), navajas (razor clams) and fried camembert.

Also, if you are looking for reasonably priced Catalan restaurants, Bodega Manolo, Bar Cañete or Casa Delfín are options.

Buen provecho!

(Note: photo is of tapas generally but it won't let me choose that, just one of the restos. It's not from one of the restos, just a photo I took elsewhere in Barcelona of tapas :)

Ciudad Condal. Great food packed with locals and tourists alike.

Hi! I'm from Barcelona and this would be my list:

Taktika Berri: Ideal for pintxos or montaditos in Eixample

S.I. Bar Ramón 1939 S.C.P.: Catalan tapas at good quality/price in Sant Antoni

La Cova Fumada: Fresh fish & catalan tapas in Barceloneta

You can check more in my Barcelona tapas map

Of course as people said here other good options but more expensive are:

Bar Cañete

Bar del Pla

Cervecería Catalana

Ciudad Condal

I guess you already found my answer in the other blog... Download the freebie guide on my books page :-)

Still I would like to recommend one more tapas bar I love: Obsessions del Raval on Calle De La Riereta 15. Close to Rambla de Raval.

If you really on a lean budget you need to try Bar Electricitat on Carrer de la Atlantida 61.

All the other goodies: Free Tapa Guide on my books page --> #BCN - by locals

Hi Daan, I would recommend you La Esquinica. This is a very famous tapas bar plus it's really good (and cheap!) It's about 15 minutes from the Diagonal metroline and worth every penny. As well, you can try El Jabalí tapas bar at Sant Antoni metro station. Have fun!

Onix Rambla Hotel, Hotel Acta Splendid

Try Mussol restaurant. great tapas and sangria. 

I found delicious tapas and not so expensive sangria in Poble Espanyol de Montjuic. There are many tours or buses that lead you there.

Cervecería Catalana is the best!

My favorite tapas in Barcelona is at Lonja de Tapas at: Pla de Palau 7, 08003, Barcelona

They also have a couple other locations around the city that you can find on their website: lonjadetapas.es

Tapas 24.  

Best place for Tapas hands down is Quimet & Quimet, it is in a small neighborhood but incredible!! 

Ciudad Condal. I00 percent. I go there every year at least 4 to 5 times and it is always great. Lots of locals. Also, as mentioned El Quim de la Boqueria towards the back on the left of La Boqueria.

Jodi's right; go Quim de El Quim de la Boqueria. Hands down.

Had some right on the beach.

Tapas 24 Local, not very $$ and a great menu. We went here at least twice. 

The best place is Cervecería Catalana!! The food is more than deliciouss and beer, wine or sangria are affordable.

Tapas 24 was a great find for a budget traveler like me, ended up going there thrice.

I would go to Ciudad Condal if I were you! We went there last summer and it was great.