The Maxx 5.5 is a much better knife than the X2. The X2 isn't bad, but the blade is too thin for that size and can bend or break, which mine did. Also, the lock on the X2 can be released during chopping.
The Camillus has better steel, smoother action and better construction, including a strong frame lock.
Where I like the X2 better is in the handle: The Maxx 5.5 has a thin, flat handle. The X2 is wider, more rounded and more comfortable. The X2 handle is much longer than the Maxx 5.5, giving you more leverage for chopping.
The Maxx is easier to carry concealed.