The two current and past Democratic US Senators significantly below these two, but also substantially above all other current and past Democratic US Senators are:
***** #3 Hillary Clinton
***** #4 Ron Wyden
The main reason the broadly experienced, politically perceptive Clinton is not close to the Top Two is that her past voting record on Income Inequality is at least somewhat suspect. For one of more than just a few illustrations, when you check out the US Senate past votes, New York Senator Hillary Clinton consistently voted year after year for the massively Income Inequality Expanding Tax Loophole Extenders.
The main reason that the very bright, financially astute, principled Ron Wyden is not in the Top Two at the present time is that he needs much more visibility to a National audience. To his credit more than anyone in the US Congress, Wyden is precisely where the US citizens are on US Government overreach in surveillance on its citizens.
There is one US House Member who I think is below the above Top Two but significantly above #3 and #4.....Chris Van Hollen. What a fantastic communicator and precisely where the country is on Income Inequality.
By far the most qualified of the Democratic US Governors is Deval Patrick. The problem here is that he promised his family that he would stay away from running for political office for a spell.
The most qualified of the Big City Mayors is Bill de Blasio. Income Inequality is precisely in his Wheelhouse.
There is one US Cabinet Secretary who is just barely short of the Top Two in being the Most Qualified to be US President.....Sylvia Burwell. She is so incredibly talented and versatile. And everyone, even Republicans, really like working with her. If she can get even some more Republican State Governors to increase their State's health care coverage of their uninsured citizens, then she would probably move into the Top Three category with Warren and Brown, due to the resultant substantial Income Inequality Narrowing.
I can think of at least two Executives now in the private sector who have the Requisite US Presidential Traits and would make very effective US Presidents..... Starbucks CEO Howard Schultz and Facebook #2 Sheryl Sandberg. I'm certain there are many more.
There is one exceptionally gifted person who has fixed huge messes in the US Government and also was previously an outstanding CEO in the private sector. Probably above all others in the potential Presidential Candidate mix, Jeff Zientz has the critically needed Presidential Trait of being able to process so much complex information quickly. Zientz's leadership in fixing the disastrous healthcare.gov website last year resulted in just massive Income Inequality Narrowing.
So when you put the above eleven people together, and add in Independent Bernie Sanders, you get my Top Dozen List of the Most Qualified and Most Likely To Win US Presidential Candidates.
Now if we could only get all twelve of them to run for US President.