All of them are important if you wish to stay out of trouble.

Never use funds of others. Follow the rules in your state.

All of them are equally important. 

They are ALL important.  

All fiduciary duties are important!

The most important fiduciary duty is; ALL Of Them. 

The one you violate and causes you to lose your license is the most important one to you!

The one you ignore will become the most important one.

They are all equally important, no one is above the others unless they are all followed

If you were on the spot to answer this for yourself you could do it easily. Why? Its a common sense answer not a learned one. Ask yourself this: What would take place without Fiduciary? Without trust? How far would we get? How about no honesty, integrity or righteousness? We would all be dead by now...Study up on the intellectual stuff but always believe sense

most important fiduciary duty

Undivided Loyalty- without it ya got nothing