We need to know more...
How much do you want to spend and what kind of material will you be cutting and / or chopping?
You mentioned it dosen't need to be pretty so I'm assuming you have a need for an efficient cutting/chopping tool.
I have not found one single knife that can do eveything as well as tools designed specifically for their task.
For light chopping, the best tool I have ever used is the Gransfors Bruks Small Forest Axe - $65.00
For clearing a path thru a web of thin vegetation or branches, the best tool is a simple 18" US issue machete - $25.00
Total $90.00...there is not one single knife that will out-perform this combination.
If your reason is simply because you want a big knife, which is a valid reason, buy only what you like.
Cheers,
Collecter