Q:

What are the default protection levels of different bindings in wcf

I gone through the MSDN Document, and found the following : -

But they had not mentioned the default protection level of each binding. 
Can any one let me know the default protection level of each binding. 

A:

You can set the Protection Level depending on your needs, I dont think its a case of this goes best with that, it depends on your situation.  
None - Authentication only. 
Sign - Sign data to help ensure the integrity of transmitted data. 
EncryptAndSign - Encrypt and sign data to help ensure the confidentiality and integrity of transmitted data.   
In the article its mentions:

If you select a binding that does not have security enabled (for
  example, the BasicHttpBinding class has security disabled by default),
  and the ProtectionLevel is not explicitly set, then none of the
  application data will be protected. 

Hence if you choose a binding that has, for example, disabled security by default and you dont explictly set the ProtectionLevel - none of the data will be protected - and that's what I mean there is no default. 
Edit: This article has a couple of tables that shows you the comparison and should hopefully sort out the confusion: Configuring System-Provided Bindings

