There is no single price at which Marbella property becomes luxury. A €1 million penthouse can be genuinely luxurious while a €3 million villa can simply be expensive.
True luxury usually comes from a combination of location, architecture, quality, craftsmanship, privacy, security, views, condition and lifestyle.
The better starting point is not “Which is Marbella’s most luxurious area?” but “What kind of luxury do I actually want?”