It depends on what your intention or need is. Different saints are known for certain intercessions.
However, I would counsel against “wishing for a miracle” so to speak, as a novena should not be viewed or utilized as a type of magic spell to make something happen, despite the popular use of them as such.
Also, the efficacy of a novena may also be dependent upon your state of grace, concentration in prayer, and severity of your intention.
Some others are probably more knowledgeable than me. These are just my guesses and opinions.