I'd rate them all ahead of Clinton and Obama. Nixon being third last.
Nixon resigned before a hearing could be heard for impeachment.
According to what I've read, Clinton was the only president to ever have
an impeachment hearing, and to be impeached. (Three levels of
impeachment: warning, weakened powers, removal from office). He went
through at least the first level. He also made a pile of promises, and
didn't deliver.
Obama: the first two bills that he issued put America three times lower than the worst Bush Jr. deficit. He reversed so many campaign promises, and he can't make a decision half of the time and stick with it. The only thing that he is good for (which is what he has in common with Clinton) is that he is a public speaker, and tells the people what they want to hear. He isn't as effective in the offices, just to the public.
CNN even made a skeptical comment about the overall grade that Obama
received for his first 100 days. Considering that the people thought
that the economy was getting better at the time, when it got a lot
worse since Obama came into office. All of the banks that folded,
all of the homes that were foreclosed. It was on CNN.

One more thing......If Bush Jr. was that bad, he would have been
impeached before his first term was even over. Mainstream media
has forced anti-Bush material on the public since he decided to send
troops to the Middle East, and because he's not a public speaker;
rather than discussing the other half of the issues, and rather than reporting the good things he did in office.

Clinton is the only one to have been through the impeachment process
in part. Therefore, he is the worst in my mind, tied with Obama. Then
Nixon. The rest of my list pretty much looks like the original post.