The 3a bank account
This is the simplest option: a dedicated account, funded freely, with no obligation to pay in from one year to the next. Returns are modest (often 0.5 to 1%), but the capital is available at the planned maturities and you are tied to no commitment. It is the default choice to start, or for those who value freedom.
The securities solution (3a funds)
Here your 3a is invested in funds. Over a long horizon, expected returns are markedly higher (historically 2 to 7% depending on the allocation), at the price of volatility you must accept. This option suits those whose retirement horizon is distant and who can ride out market swings without panicking.
The insurance third pillar
An insurance contract blends savings and protection: it can include death or disability cover, and sometimes a payment guarantee. In return it is more rigid (often contractual contributions, fees and penalties for early cancellation). It is aimed at those who want to protect their family while they save.
How to choose in practice
There is no universal answer: it all depends on your horizon, your risk tolerance and your need for protection. Many people in fact combine approaches (for instance a bank account and a securities solution). The right reflex: compare offers over the real term and check the fees, rather than relying on the headline rate alone.