EH Bildu
Erabaki, para avanzar.
I think that with this phrase EH Bildu wants to transmit that if you choose them, you'll have the oportunity to decide and to change the situation of Spain. To make a step forward. Also the candidates are influential people (one of them is the mother of one of Altsasu prisoners).
I think it isn't appropiate because of the language. Having the half of the slogan in Basque and the other in Spanish is not a good idea. I think it would be better if they put everything in Spanish or everything in Basque.
ERC
Va de llibertat.
This slogan obviously mentions the situation of Catalunya with the independence and the political prisoners. Futhermore, Oriol Junqueras (one of the candidates) is in prison.
I think that this slogan wants to transmit that if you choose them, they will fight for the independence and the situation with the political prisoners.
Podemos
La historia la escribes tú.
I think that podemos wants to transmit that the votants have the right to make their own decisions and to change the actual situation of Spain.
I think is a good slogan because many people nowadays, especially young people, want to change the law and rights: with the homosexual, inmigrants and so on.