I can only highly recommend Casa Valeta- I spent 2.5 weeks there with my family and we were all extremely pleased with the flat. Here is why:
-The location is ideal (you can literally walk anywhere in Barcelona)
-The apartment is beautiful (high ceiling, quiet, huge, very clean, and the terrace is big!)
-The flat is perfectly furnished (washing machine, dishwasher, hairdryer, coffee, tea, even detergent products!)
-Marina and Martin are fantastic guests, it is the cherry on the top I guess (they are present, friendly, always there to help/give some tips and they have lovely attentions during the stay)
I will definitely book Casa Valeta again when I am back to Barcelona, nicely done Marina and Martin and hasta luego :)