I'll muddy the waters a bit more...
Huck with fusion handle is a good deal more comfortable for me when chopping than the regular Huck. It's smaller, however.
The 1311 was WAY more ergonomic <and practical> for me than both models, that's why I don't own either Khuk now....ymmv.
I have not owned, nor swung, a KillaZilla.
Muddy water noted.
The 1311 is my most used yard knife. I wish they made a version with a Regulator handle.
The Fusion Handle HUCK looks cool but it has the fin which I'm not really into...