Reason is good, but it's only as good as our scope of knowledge. Tradition is likewise good, and God used traditions to pass down history in the holidays and rituals of the Old Testiment. So traditions are also good because they can be from wisdom passed down that a person can take the benifit from without fully understanding it. But I would still say that scripture is more important still. I would count scripture as a higher degree of authority capable of correcting the other too. My reasoning comes from two verses. In Mathew 5:17-20 Jesus tells that has not come to abolish the law and that no aspect written in the law will disappear until all is acomplished. Paul in
2 Timothy 3:16-17 explains that all scripture is God breathed, or inspired by God (depending on the wording of the translation).
For context of of
2 Timothy 3:16-17 I would also like to consider the chapter as a whole. Verses one through nine speak about what kind of people will be in the last days. Verse 5 says to have nothing to do with them, and verse 9 explains that that they won't get very far I their wickedness because everyone can see through their folly. Take note of verse 5 though and it's last discription of the people of that time. To have a form of godliness but denying it's power. Moving on to the second half of
2 Timothy 3. Verses 10-17 are Paul's encouragements to Timothy to encourage him in what he already knows. That the scripture is God breathed and good for teaching, rebuking, and training in rightousness.
With these in mind I would lean on scriptures more then I would tradition or on our own reasoning. Though I don't mean to cast those aside, but put them in their place comparatively.