What type of Logia can defeat a Haki user? What type of Logia can defeat a Haki user?

Some Logia users are hard to defeat. Fleet Admiral Sakazuki a.k.a. Akainu, and Former Admiral Kuzan a.k.a. Aokiji are some examples.
There is no such thing as a Devil's Fruit that automatically beats a Haki user.  The use of Haki is to be able to make contact with a Logia type fruit user.  This allows for a "fair" fight (in the sense that one person isn't inherently untouchable).  However, there is no fruit that negates the power of Haki (or at least among the fruits that have been revealed).