We own at both LaCabana and Costa Linda but have not stayed at either resort yet since buying our weeks. However based on my knowledge of Aruba I would agree with Costa Linda as a better choice since it is right on the beach as opposed to being across the road at LaCabana. Both resorts are going to have a major renovation with LaCabana already started. In fact the unit we purchased at LaCabana has already been renovated so we will be using it this January. Costa Linda's renovations will not start till 2010 so that would also be a consideration and if you can get a renovated unit at LaCabana I would grab it.
There is a renovation schedule at LaCabana's website but I'm not sure if you need to be an owner to see it. I can check the website and let you know.
In either case both resorts have great beaches with the edge to Costa Linda and you will be happy with either resort.