if(this == obj)

There are:

• QFix: cast obj to type of this and still use operator ==.
• CA: use Equals.

Missing:

• Use ReferenceEquals.

Also the problem is that one is a QFix and another is a CA, while it's hard to tell why one is more important than another.

The new ReferenceEquals QFix/CA should have highest priority of all (go the first in the list, possibly thus a QFix), because it does not change the code logic and won't lead to StackOveflowException in case of a recursive ==—Equals call.