I think that a secular institute is a better option than a third order secular, and perhaps a third order regular or life as a religious brother better still.
The reason being, these lifestyles mean adopting the evangelical councils (those vows, which are nothing less than Jesus Christ’s own advice on how to most easily live a happy Christian life). In a secular institute, you live in the world, with your own apartment or house and secular job, but still following a rule. In a community, you live in common with your brothers, with their presence there to support you, and as a model for you. Which is more appealing depends a lot on your personality, and which life will provide you with what you need to be happy.
SSA or no SSA, though, chastity is always a gift of God, not something we do on our own. Therefore I would recommend anyone who knows that married life is not for them to look for a community, whether a religious order or a secular institute, to provide that Christian family that we all need in our adult life to be fulfilled.