I use this one:

And I'm happy with it. It does what it's supposed to do: cut lines and some cords. I have used it a couple of times underwater for that, mainly because the anchor gets entangled and can't close when we're folding it in the end of the dive.
In my opinion it's the right size and as it is a fixed blade there's no mess opening and closing it with gloves. Not the cheaper option, but hey, I'm a knife nut!!!
http://www.mission-knives.com/index.php?main_page=product_info&cPath=18&products_id=50

And I'm happy with it. It does what it's supposed to do: cut lines and some cords. I have used it a couple of times underwater for that, mainly because the anchor gets entangled and can't close when we're folding it in the end of the dive.
In my opinion it's the right size and as it is a fixed blade there's no mess opening and closing it with gloves. Not the cheaper option, but hey, I'm a knife nut!!!
http://www.mission-knives.com/index.php?main_page=product_info&cPath=18&products_id=50