The best for location are:

Tryp Habana Libre (previously the Hilton) now the pool is under complete destruction for renovation

Hotel Nacional (nothing Nacional about it, it has roaches)

or

Melia Cohiba with a huge pool

Now if you want something better and can pay(I would not), then select:

Hotel Saratoga the owners were recently arrested by Cuban authorities was in the news (really over priced but very nice)

Also good:

Hotel Parque Central with a rooftop pool and the best pizza's (formerly owned by the NH group now by Cuba), try to get the new tower.

I repeat do not stay anywhere else if this is your first time!!!