That entirely depends on what meaning matters most. See, Symbols in themselves are just physical tokens, they have no meaning, but that which we ascribe to them. Thats why they can have more then one meaning, or how meanings can be perverted over time. Symbols are merely ikons, or signposts which point to something greater then themselves (that thing which they symbolize.
so the question is not which Number is the most important symbologically...but what THING is most important, and by what token is it represented.
To me...I would have to say the nature of my walk with GOD through the seasons of my life, in order to eventually gain union would be the most important meaning. The closest numerical value for this would be Forty. Often a long period of time, which represents preparation, or a season between two changes, or a time of growth...part of a journey.
it rained for forty days...Christ was in the wilderness for forty days...each a season for something...
That would be my answer.