We stayed in the Costa Sal apartments 2 years ago. We paid the extra money for a refurbished room and it was worth it as the other apartments were dated looking. Good entertainment there 6 nights a week.
They are in Matagorda, a walk down a hill to the beach, they are about 10/15 mins walk to the Matagorda Centre which has a good range of bars and restaurants. €6 for a cab into Puerto del Carmen. We walked in and out every day and it was at least 45 mins each way.
I have not stayed in the Montana so can't comment on them. Last October we stayed in the La Morana apartments (see my review) and we preferred being in the New Town as you are in the centre of everything without needing taxis.